0410: Lovely stuff. The dream final remains on the cards, as does Djokovic v Youzhny if that floats your boat. It's over to the women in a little over 13 hours for the semi-finals from 1730 BST, with David Ornstein here to take you through Caroline Wozniacki v Vera Zvonareva followed by Kim Clijsters v Venus Williams. I will be entering a decompression chamber in preparation for Super Saturday, can't wait.

From Andy in Portsmouth via text: "So who will win if Federer and Nadal are both at the top of their game (well I can hope). My money's on Fed in 4. Can't wait."

Times correspondent Neil Harman on Twitter: "Rafael Nadal into the sfs to play Youzhny. Would not want to be in Mikhail's shoes. Nadal to win the title..."

0402: "It was very difficult to play, one of the most difficult days," says Rafael Nadal, "and Fernando had a really tough match the other day. "The serve was important but it was very difficult when you throw the ball up to control it. The movements are very important and I tried all the time to be very concentrated and wait for the mistakes of the opponent. It's very important for me to make the semi-finals again. It's very nice to be in the semi-finals three times in a row at one of the most important tournaments of the world, probably for me right now the most important."

Nadal 7-5 6-3 6-4 Verdasco
Verdasco gets the crowd going with a beautiful heavy-topspin lob that Nadal tries and fails to chase down, but a big serve and a Nando error take the top seed to two match points.... and there we have it, Nadal seals victory when Verdasco nets and it's Mikhail Youzhny next in the semi-finals. Anyone backing Mikhail?

* Nadal 7-5 6-3 5-4 Verdasco
Nadal opens the game by doing a 360 while playing a half-volley and wining the point. Who does he think he is, Gael Monfils? Verdasco is having none of it and sees out the game. Rafa to serve for the match....

Nadal 7-5 6-3 5-3 Verdasco *
Cheeky. Nadal gets to 30-0 with a deft forehand drop shot. Verdasco just shrugs and wanders over to receive serve again. He then wallops a backhand long before Nadal rubs salt in the wound by returning a vicious Verdasco forehand from on top of the net and winning the point. Nando slams his racket into the ground and I'm not sensing a repeat of his five-set comeback against Ferrer - or Ferrdasco, as it is now known.

* Nadal 7-5 6-3 4-3 Verdasco
Verdasco is relieved to see a volley bounce off the top of the net and fall on the other side of the net as he holds to 15.

Nadal 7-5 6-3 4-2 Verdasco *
Another easy hold for Nadal, who's morphing into a 1990s-style Goran or Sampras, such is his dominance on serve. If anyone's likely to break at the moment, it's Rafa.

stu_fraser on Twitter: "Hate 2 look ahead but pumped 4 the Federer V Nadal final which is surely on the cards! Cud b insane goin by their form so far!"

* Nadal 7-5 6-3 3-2 Verdasco
Verdasco could be forgiven for waving a Nadal pass through at 0-30 but he plays a superb lunging volley and comes back to take the game. You wouldn't call it a comeback but he's still in this.

Nadal 7-5 6-3 3-1 Verdasco *
Nadal closes out another service game with a nice rally, helped by a net cord on game point that leaves Verdasco out of position. The man from Madrid tosses his racket high into the air in frustration. That won't help, Nando, but we understand.

* Nadal 7-5 6-3 2-1 Verdasco
A fifth double fault of the night doesn't bode well for Verdasco but he comes through to stay just about in touch.

Nadal 7-5 6-3 2-0 Verdasco *
Verdasco gives it a little bit of fist pump after cracking a forehand winner that nearly knocks Nadal's racket out of his hand at the net. Rafa isn't bothered though, and barrels into the net on game point to play a superb half-volley that Nando can only blast long.

From Lionel via text: "I went to sleep when Verdasco was 2 sets down against Ferrer. It's safe to sleep this time isn't it? ISN'T IT?"

* Nadal 7-5 6-3 1-0 Verdasco
Dangers signs when Verdasco plays a woeful volley for 0-30, and two points later he's lobbed by Nadal and - much to everyone's disappointment - fails to 'do a Roger' and hit a winner after chasing it down. Two break points for Nadal... and Nando stays rock solid at the net to save the first, only to flail at a forehand around his shoulders and punt it over the baseline on the second. Any way back for Verdasco from here? Anyone?
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Nadal 7-5 6-3 Verdasco *
A wide serve opens up the court, a big forehand drives his opponent back, and a smash finishes the job. That's the way Nadal gets to 30-0, and Verdasco then hits a backhand so far wide he screams like a toddler. Three set points.. and Nadal hooks one of his best forehands of the day cross-court for a clean winner.

* Nadal 7-5 5-3 Verdasco
Verdasco keeps his man honest by holding serve and forcing Nadal to see out the set.

Nadal 7-5 5-2 Verdasco *
When I'm involved in a tense match in the park with a friend, I like to use mind games by repeating the words of the great Ivan Drago from Rocky IV before my opponent's important service games, shouting "I must break you!" in a sinister Russian accent. I would suggest Nando does the same here but it's too late for this game. Rafa holds quickly and this set looks like it's nearly done.

* Nadal 7-5 4-2 Verdasco
Verdasco wears a thin smile on his way back to serve after Nadal plays a killer drop-shot-return, thanks to a combination of the wind and mistiming the ball. Deuce, and Nadal has a great chance to pass on the forehand side but finds the net. It's hard to decide who's more disgusted, Rafa or Toni. Verdasco then dumps a very makeable mid-court forehand in the net and it's break point.... Nadal comes in, plays a drop volley and Nando comes haring in just as he did on match point against Ferrer, but this time he goes wide and Rafa is in total control now.

Nadal 7-5 3-2 Verdasco *
An absolutely fizzing forehand from Nadal on the run, if anything backwards, takes the world number one to 40-0 and Verdasco cannot control a body serve as the game races by him.

Nadal 7-5 3-2 Verdasco *
An absolutely fizzing forehand from Nadal on the run, if anything backwards, takes the world number one to 40-0 and Verdasco cannot control a body serve as the game races by him.

* Nadal 7-5 2-2 Verdasco
There's plenty of grunting as Verdasco muscles his way to a straightforward hold.
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Nadal 7-5 2-1 Verdasco *
Nadal whips a forehand cross-court at 30-0 and Verdasco shanks it when trying to respond in kind. It's very quiet out there, scrappy stuff on court, until Rafa chases one down out wide and hammers a forehand winner up the line. Great shot.
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From Michael, Ireland, via text: "Not that impressed with Rafa so far. Verdasco lost that set by understandably being unable to get a first. While I credit Rafa for serving well, Nando has been better in the rallies."

* Nadal 7-5 1-1 Verdasco
Nadal needs the towel at one point to wipe something from his eye, presumably debris left by the howling gale out there. He's then interrupted mid-rally by what seems to have been someone blurting out something over the PA. Maybe it was Roger trying to put him off. No matter, Verdasco holds to 15 and Uncle Toni continues to shiver away in the stands. Wasn't everyone complaining about the heat in New York last week?
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5 live's Jonathan Overend on Twitter: "If this goes to 5 it could match the Aussie epic! Really cold out here. Not always pretty but absolutely fascinating."

Nadal 7-5 1-0 Verdasco *
Nadal opens the second set with a comfortable service game, despite belting one forehand several feet long.
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* Nadal 7-5 Verdasco
Oh dear. Verdasco is 0-15 down and then plays a great rally, only to snatch at an attempted volley/smash and frame it into the crowd. I was sitting nearby when he did something similar at the Tour Finals in London last year, nearly knocked the umpire off his chair. Another error has Nadal at 0-40 and three set points... and the top seed plays one of his best rallies of the night to close it out at the net. And if Verdasco can't win a set like that, you have to wonder...

Nadal 6-5 Verdasco *
Verdasco gets under a sliced backhand and it takes off with the wind, probably still heading upwards now as it leaves New York airspace. A love game is sealed by Nadal with another ace and the ball is, quite literally, in Verdasco's court.

* Nadal 5-5 Verdasco
Nadal mistimes one return that sends the ball flying back like a Cristiano Ronaldo free-kick (i.e. moving a lot in the air, not walloped over the crossbar). Rafa does well to get a racquet on a wide serve at 30-15 and Verdasco cannot handle it dropping right on the baseline. It's 30-30, and the pressure is really on Nando, but he comes through impressively to hold.

bigmananand on Twitter: "He did need another break i think for him to beat nadal hes gonna need quite a few with the form hes in."

Nadal 5-4 Verdasco *
Nadal hits his first ace of the day for 15-15, flops a tame backhand into the net, and then hits his second ace of the day for 30-30. We get to deuce, and the big-serving Rafa returns to force game point before the Majorcan moves to the net and plays a very careful volley to seal the game. Three games in a row for the top seed.

* Nadal 4-4 Verdasco
Thwack. Verdasco gets up on a forehand and absolutely belts it down the line for 30-15, but two errors follow and Nadal has his fourth break point of the day..... but Verdasco takes control with a big serve and pummels the forehand to take the point. Ay ay ay... a huge double fault gives Nadal a second break point.... Nando swings a serve out wide that's called good, only for Hawkeye to overrule, and the second serve is walloped into the net. We're all square.

From Paul in Sydney via text: "Why did so many people doubt Verdasco? i still clearly remember the semi final of the Aussie open 2009 where Nadal scraped through 3-2. Could have gone either way! I put a small count on Nando to win! Long long way to go yet!"

Nadal 3-4 Verdasco *
A quick hold for Nadal - who thinks Verdasco needs another break?

* Nadal 2-4 Verdasco
Tidy stuff from Verdasco, who appears to be handling the wind much better than Nadal, and the man from Madrid remains in charge. His dad and supporters are helpfully all wearing the same tracksuit tops in the stands, although disappointingly not with a big picture of their man on the front a la Papa Djokovic.

Glen in kinsley yorkshire via text: "What is it with professional sports people that can't play in condition's we mortals practice in every day."

Nadal 2-3 Verdasco *
Nadal goes for the same forehand he tried on break point in the previous game and this time clips the line for 30-0. A solid hold.

* Nadal 1-3 Verdasco
And to think, some doubted Verdasco tonight. Where are they now, eh? The eighth seed consolidates his break and he's bossing it at the moment. Nadal races in and swats away a backhand for deuce and moments later has a break point.... but he mistimes a forehand badly in the wind and it flies over the baseline, and the chance is gone.

Serena Williams on Twitter: "Are you Ready for some football!!!!!!!!!!!!! "

Nadal 1-2 Verdasco *
That's what we're all staying up for... Verdasco cracks a forehand up the line, a backhand cross-court and a backhand up the line for three break points... and Nadal nets a forehand! The world number one drops serve for the first time this fortnight. The good news is, it looks like he's going to play on. I'd have stormed off in a huff by now.

Grant from Edinburgh via text: "Waiting for a lift to the airport in tallinn. Wanting an upset but just can't see it."

* Nadal 1-1 Verdasco
The wind is playing a part already as Verdasco ends up playing an early backhand from near his armpit as the ball veers in towards him, setting up a very loose volley. Nando's in trouble at 30-30 after a forehand into the tramlines and when he sends one long it's break point..... Verdasco breaks off during his service motion because of the wind, shaking his head and appearing to look for sympathy from Nadal. He steadies himself to hit a forehand winner for deuce but we then get two double faults in a row. Break point number two... second serve.... but Verdasco does really well to win a tense rally with a forehand into the corner and eventually takes the game.

Nadal 1-0 Verdasco *
I can confirm that Nadal has still not dropped serve in the tournament. He opens with a love hold as Verdasco fails to control a couple of forehands.
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padawanbeck84 on Twitter: "Can I give a big shout to the rest of the Rafateers from the BBC 606 forum? We're all staying up to support our favourite."

0123: OK, we're getting a few making the case for Verdasco, with his massive forehand. Both men are men are hopping from foot to foot at the coin toss, possibly because it's a bit parky and, as ever, blowing a gale. By the way, a manual refresh will create illusion that Mark Ashenden has left, although he's actually just made me a cuppa. Before leaving.

0120: I see tennis players! Verdasco is in white tonight, Nadal in black. Helpful for anyone watching this live text commentary in black and white.

From Max, Hants, via text: "Evenin' (err Mornin') Piers enjoyed your company last night and looking forward to a re-run. Rafa in 4 sets watdoyafink?"
I'm going for Rafa in three, hoping for anyone in five. If my sleep pattern is this messed up, might as well make the best of it.

Herbasaurus on Twitter: "Go Verdasco, always gotta feel for the underdog."

0111: So who's up for a five-hour epic like Australia 2009, eh? Stick with me for the duration and give me your thoughts via Twitter or text on 81111 (UK) or 44 7786200666 (worldwide) with TENNIS before your message.

From anon via text: "Piers, you've got 50 words to convince me to stay up for a bit longer. It's Eid tomorrow, I need to sleep!"
All I can say is, if Nadal gets anywhere near the level of Federer last night it's not to be missed. And if Verdasco wins, you'll have missed one of the shocks of the year. How many's that?

0102: Having said that, I can't really see how anyone can make a case for Verdasco. Nadal leads the head-to-head 10-0; he hasn't dropped serve, let alone a set, so far; and Verdasco has battled through two five-setters. Anyone backing Nando?

0056: Hola. It's taken a while but we're ready for the last of the quarter-finals between Rafael Nadal and Fernando Verdasco. It could have been even later if they hadn't mercifully decided to move the proposed exhibition match between Hingis/Kournikova & Cash/Woodforde until after the main event. It's been harsh on Spanish viewers this fortnight as Rafa, in particular, has been almost a fixture of the night sessions. Still, it's their own fault for being so ruddy good at tennis, and in my experience the Spanish are not afraid of a late night. This one should be worth staying up for anyway.

0047: Anybody know a finger massage specialist for my burning finger tips? What a match. Four hours. Not pretty. A handful of fireworks. I think Youzhny has the better chance against Nadal - a few more shots in his locker. So I bid you farewell and hand the rudder of this rather wobbly ship over to Piers Newbery. He will guide you through gently over the choppy waters that sees Rafa Nadal go up against Spanish compatriot Verdasco. Thanks for all your contributions. Brilliant. Night.

0041: Russian Mikhail Youzhny makes the semis with a 3-6 7-6 (9-7) 3-6 6-3 6-3 win over Stanislas Wawrinka. The 12th seed will play the winner of the match between top seed Rafael Nadal and fellow Spaniard and eighth seed Fernando Verdasco for a place in the final. Love it.

Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 3-6 Youzhny
Youzhny edges towards victory as the ball lands on the line. That's a heart-buster for Stan. 0-30. His smile has officially disappeared. He battles back to 15-30. Any hope? And he goes long. 15-40 and two match points. And as the clock reads four HOURS - yes FOUR HOURS, Youzhny makes it. YOUZHNY WINS. What a mammoth effort all round. And I mean you guys as well. Who's off to bed? Are you joking? Rafa's next up....
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Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 3-5 Youzhny
Youzhny smashes the ball down to take the first point. Big cheers. Even his coach is punching the air. Is this the end of Stan? Any headlines with "Brave Stan" in it? Game over. Big boos. Stan ploughs the ball into the net and guess what? That graphic's coming back....TWICE. That racquet is in a bit of a state. Serving to stay in the match.
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Wawrinka 6-3 6-7 (7-9) 6-3 3-6 3-4 *Youzhny
Lob-tastic. Another item flies out of Youzhny's top drawer. A few pants were coming out of his furniture earlier on but he's producing the goods in this set. A break point for the Russian. Is the Swiss defence waning? More pitter-patter from Wawrinka but it pays off. Youzhny playing ALL the shots but that one ploughs into the net. Stan blows his chance though. ADV Youzhny. Is this the moment this match turns for one final time? Stan grinds out a forehand that leaves the Russian on his hands and knees. DEUCE. Any more shocks? Three hours 50 and Stan dishes up a corker and then he goes for a walk into the net and plays a winner. Great battle. Seriously. Where has he got that energy from. He's playing on empty. And as a few of you have mentioned - the prize for winning this? Nadal or Verdasco. If Wawrinka wins this I'd be surprised if he's not carted on to Arthur Ashe via a helicopter at the weekend.
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Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 2-4 Youzhny
Stan bouncing on his toes, trying to drum up a fresh gear in his weary Swiss legs. And talking of Youzhny's backhand. It's a scorcher as he pulls one into the far corner and Stan has no chance. It limps into the net and it's game point. Game over and Stan looks a little grumpy. We've said that before tonight though. A whole bag of twists and turns. Magical drama.
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Glen in West Yorkshire, via text 81111: "I've no school tomorrow. No dissertation to write, just a nagging wife wondering when I'm off to bed . Not till Rafa the gaffa has played. Will you please tell her mark."
I'm not getting involved in your domestics. Surely the wife fancies a view of Rafa's guns? Use your head son. Use your charms and magic. Let me know how you get on. Believe, focus and perform like a Youzhny backhand.

Wawrinka 6-3 6-7 (7-9) 6-3 3-6 2-3 *Youzhny
Youzhny nicks the first point but then his strength gets the better of him - a wild one and it's 15-15. Who's tense out there? Where are you? Why are you still up? Talk to me. Piers Newbery's here waiting for the Rafa Nadal game and he's going to need some company for that match. Forget your dissertations. Forget work tomorrow. Tomorrow's another day. TODAY is still Thursday. Until today ends. Jump on board. We'll keep you awake. And Youzhny hits back with another break. The crowd go wild. Anybody going wild out there in these wee early hours?
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DannyTheJourno on Twitter: "Loving this match, not the greatest quality tennis - but somehow just enthralling. Come on Mikhail!"
Couldn't possibly argue with your sentiments.

Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 2-2 Youzhny
A lively game this one. Last chance saloon for these boys. For one of them, this is the last set they'll play at this year's US Open. Worth forgetting those aching limbs don't you think? And the stadium is rocking as Stan stands strong at the net after a number of defensive shots and he powers it back at Youzhny's feet. Two break points. Game on. And Stan has a chance but he blows it long. 30-40. Interesting. This match just went from warm to el scorchio. Stan waves his racquet in the air and he grits his teeth. He's one happy Swiss boy. Rightly so. Youzhny is rattled. The trainer comes on for Youzhny and tends to a swollen toe. I think. Blisters maybe? Or is the tan spray coming out? Those tan marks above his socks are a disgrace! Not a fan of the exclamation mark but those Russian feet have warranted one - hope you're OK with that.
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Kevin in Durham, via text 81111: "Masters dissertation due in tomorrow. Still got the intro and conclusion to write. Why am I still reading this live text!?!"
Because you love your sport. Because sport matters. Because sport is more important than life. Because even if you went to bed, you'd lie there for an hour wondering what the hell was going on at the US Open. You'd end up not sleeping. You'd wake up even more tired. I can't condone late nights affecting your dissertations but you're doing the right thing. But please read the small print that excludes me from any responsibility if you only get a B- for your piece of work. Good luck with it though.

Wawrinka 6-3 6-7 (7-9) 6-3 3-6 1-2 *Youzhny
I've just realised I had the broken raquet in the last few games. Sorry folks. You must have thought these two were having a right old strop. Not so. My graphic error. Stan has it all to do and he's struggling at 15-30. But he's still got some fire in his belly and he smashes at the net to get it level 30-30. A big serve gets him out of trouble and he's still fighting. Youzhny pulls a couple of crackers out of that top drawer again - Stan is scrambling across the court like a meercat and the Russian defends everything the Swiss throws at him and it's deuce. Great entertainment. This match has had its moments. A very gingerly-played point. Would you go for your shots at deuce or just defend? Stan grabs it though and he gets a number on the board. Advantage still with the Russian though.
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Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 0-2 Youzhny
Youzhny leads 40-30 and has a chance at the net but his feet stumble as Stan fights back and the Russian plants it into the net. Deucey time. It's all Youzhny so far. And he edges ahead by two games. What would you be saying to Wawrinka if you were his coach (and you had access to him at his chair?
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HardyWebster on Twitter: "I really think this could go either way. Insightful, eh!?"
There are stunning tweets and there are stunning tweets. And that was from the back of the cupboard of the top drawer. Any contenders for the day's worst tweets out there?

Wawrinka 6-3 6-7 (7-9) 6-3 3-6 0-1 *Youzhny
Who's still awake then? Who's staying up for the Rafa match? It goes to 30-30 after Stan's backhand smooches the top of the net and it flies wide. Just. They both look tired. I guess they would, wouldn't they? I am, and I'm just sitting here. And finally, Youzhny mixes it up and pushes Stan into the corner and rips the smash back. Top stuff. Be more aggressive Mikhail. That's what I'd say if I was his coach. And Youzhny gets a break with a brilliant finale to a brilliant rally. Both teasing each other with an array of dibble dabbles and missiles and Youzhny powers one towards Stan's body at the net and he gets it. Top of the top drawer.
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2344: Oh my lordy. Clock reads three hours and two minutes. It's a whopper. Unforced errors - 54:50 with Stan producing the most. 40:27 winners in Stan's favour. Back to the court. Hold on to your hats. Fifth set is upon us....any thoughts?

Wawrinka* 6-3 6-7 (7-9) 6-3 3-6 Youzhny
Stan takes the first point. Desperate stuff. Woh there Stan. He falls to the ground after slipping. Dodgy trainers? Thought that was a Azarenka fall-over moment. Relax. He's OK. Stan whacks the ball into the net and the unflappable Swiss becomes a bit flappy - he hurls his weapon to the ground. Youzhny has two set points and he takes it after Stan comes to the net after playing a pretty shocking loopy shot that lands long. Two-sets all. Where's this going?
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Wawrinka 6-3 6-7 (7-9) 6-3 3-5 *Youzhny
A scrappy start to a very important game. And that was pretty easy. An ace bags him the game. Time for Youzhny to step up to the plate, as Americans like to say.
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2335: Wawrinka leaves the court. Toilet break? A quick rub down? A quick catch-up on the latest tennis scores at the US Open. You're playing Stan. You should know the score sir. He's back. Eyes down everybody. Youzhny one game away from levelling the match.

Wawrinka* 6-3 6-7 (7-9) 6-3 2-5 Youzhny
Has Wawrinka lost his rag? Is he saving himself? He belts a backhand wildly wide and long. Youzhny leads 30-15. A double-fault gets it to 40-30. A chink of light for the Swiss 25th seed. A brilliant combination of backhands and a forehand into the corner gets Stan in all sorts of trouble and Youzhny wraps up the game with a simple cross-court volley. Nice. Five-setter anybody?
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Wawrinka 6-3 6-7 (7-9) 6-3 2-4 *Youzhny
Wawrinka looks a little troubled with his left thigh as his trainer patrols the arena. 15-15 as Stan crashes one long. The battle of the fittest. Although having said that, I thought Stan was struggling after the second set. battle of the minds perhaps. Who's your money on folks? And an ace kisses the back of the line and the lead is back to two.
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Wawrinka* 6-3 6-7 (7-9) 6-3 1-4 Youzhny
Big shouts for "STAN" as their man leads 30-15. Youzhny survives. One member of the crowd even boos. I wonder if he's waiting for the Rafa game? Time so far in this match is 162 minutes. And counting. And Stan plays long. Big relief for the Youzhny fans.
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Billy in Oxford, via text 81111: "Come on stan! I love the us open. Got school in the morning but staying up for Nadals game!"

Wawrinka 6-3 6-7 (7-9) 6-3 1-3 *Youzhny
Stan gets his act together with a big juicy bag of Swiss missiles. He holds to love.
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Wawrinka* 6-3 6-7 (7-9) 6-3 0-3 Youzhny
Youzhny takes it with some solid serving. Would I be Mr Obvious if I suggested this could be going all the way to five sets and Nadal's still in the locker room at 0200 BST?....Rafa vs Verdasco from around 0100BST. That's the plan anyway.
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Wawrinka 6-3 6-7 (7-9) 6-3 0-2 *Youzhny
Stan struggling with his serve for once. The boys mixing up the angles and Youzhny gets the break. Bit of a shock. Stan looks a little gutted. Youzhny has an extra spring in his step. Interesting.
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Wawrinka* 6-3 6-7 (7-9) 6-3 0-1 Youzhny
Youzhny gets his service game under his belt. I'm still frowning. I can't help but feel Youzhny really has blown his chance so far. Stan playing the steadier tennis and hanging in there on crucial points. Magic serve though, which has held pretty steady throughout.
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2309: Stat attack. Stan has made 9 aces to Youzhny's none. 42 unforced errors each. Nice symmetry. Stan's first serve percentage win is 79%. Youzhny is 65%. Stan has made 31 winners, to Youzhny's 23. Back to the action.

Wawrinka 6-3 6-7 (7-9) 6-3 *Youzhny
The Swiss grabs the first two points and has a great chance at the net....wallop. Youzhny gets lucky and it's 30-15. And that my friends, is a brilliant rally. And Youzhny on the back foot for 99% of it but he hits back with a stunning backhand. 30-30. A big big Swiss serve. Set point after two and a half hours...and what does he do? Nice and safe Sta. But not like that. He droops the ball into the net. DEUCE. Oh lordy lordy. A backhand lob loops beautifully over Stan..Is it? Is it?....There was me applauding a stunning winner. Nonsense. I'm wrong. It's out. Set point again. And STAN gets it. Steady.
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Wawrinka* 6-3 6-7 (7-9) 5-3 Youzhny
A pretty routine hold from the Russian. Can Wawrinka do it on his serve?
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2300: The clock chimes 11. Youzhny's US Open record. Third round on his debut in 2001. Best since then is a semi-final spot in 2006. A quarter-finalist at Roland Garros this year. Back to the action.

Wawrinka 6-3 6-7 (7-9) 5-2 *Youzhny
Youzhny has a chance to get back in the game at 0-30 but Wawrinka plays a couple of cute shots at the net and he nabs it. And he wraps up the game to love with Youzhny firing into the net. My frown has returned. I thought the Russian 12th seed was going to rip up the court after the way he finished the last set. How wrong I am.
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Wawrinka* 6-3 6-7 (7-9) 4-2 Youzhny
Youzhny survives with a firm volley at the net. A deathly hush falls on to Arthur Ashe. This is another 'big' game.
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Wawrinka 6-3 6-7 (7-9) 4-1 *Youzhny
Wawrinka may well have been saving some juice in the tank because he plays too strong points - the second sees him come into the net and rifle the ball away to lead 40-15. And he snaffles it. his three-game lead restored.
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Wawrinka* 6-3 6-7 (7-9) 3-1 Youzhny
Wawrinka slips back into sleepy mode - is he saving his legs? There was talk of a thigh injury before this match. Oh lordy - fireworks galore. Youzhny storms to the back of the court and plays a 'Federer' through-the -legs shot. Nice stuff but he aint no Roger! Wawrinka is at the net and has an easy volley...but it goes out! Awful. The Russian pulls one game back.
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Adam in Swindon, via text 81111: "Is it too late for Youzhny to show Grand Slam potential? How far could Stan go in the game?"

Wawrinka 6-3 6-7 (7-9) 3-0 *Youzhny
From fireworks to the flat sparklers that won't even light. The winds blowing in and the crowd are wrapped up in blankets and multi-coloured hoodies. Wawrinka wins his service game pretty easily in the end. Hello Mikhail. Can the Mikhail of the second set please come back.
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Wawrinka* 6-3 6-7 (7-9) 2-0 Youzhny
So much for the hurting. What about the Russian who wins a brilliant set, looks the stronger and cleverer and then plays a super-stinky service game and loses it to love by stroking the ball into the base of the net. Poor.
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Wawrinka 6-3 6-7 (7-9) 1-0 *Youzhny
Wawrinka holds his nerve and eases to his service game. He'll be hurting after that last set. Which way will this go now? A very slow start to this match but I've grown to almost love it. Great drama.
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Rich in Leicester, via text 81111: "Have u noticed Oliver Golding a set up in the doubles on court 10, thought it might be worthy of the British up arrow"
I'm afraid Arhur Ashe has been occupying my head so that's a brilliant shout-out by you. Thanks Richard. Golding playing with Jiri Vesely in the junior boys doubles quarter-finals. And HOLD ON. I check the scores and he's won. 6-1 6-3. Well done Oli.

Wawrinka 6-3 6-7 (7-9) Youzhny
Tension builds. Stan looks frustrated as he plays one long. Set point. Stan serves long. More tension. These boys are producing a lot of spin and Youzhny plays it into the net. Big groans. Wawrinka hanging on with all his Swiss might. Wonder if Roger is watching? Wonder if Rafa is watching?7-7. And that's my shot of the match so far. Youzhny pushed to the back and he plays a stunning cross-court pass that drops at Stan's feet. Brilliant. Fourth set point. And that is brilliant. Three massive shots pushing Wawrinka to make three backhand defensive shots. They get harder and bigger as he cranks up the power and the third one leaves the Swiss swiping at air. Magic point from Youzhny to take the set and level the match. One hour 53 minutes. What will that do for Warwinka's tiring legs?

Wawrinka 6-3 6-6 *Youzhny
First blood to Youzhny after a terrific rally. 1-1 after a failed over-rule request. One ball flies back to Wawrinka and it turns at right angles the Swiss keeps his gingerly defence on red alert as he edges ahead. Big noise from the crowd though as the Russian levels things out. And Stan pulls out a firecracker to level at 3-3 as they change ends. How big is this game? A whopper from Stan and he goes 4-3 up....the Swiss takes a risk and he can't believe it as the ball goes wide. Cheeky. Stay cool Stan. 4-4. Your conservative tactics have worked so far. Youzhny pumps up the pace and nicks the lead. massive. Can I say that again? Yep - massive points. Massive set. Youzhny plays a fab point, pushes it into the corner and Wawrinka cannot cope. 6-4. Warinka survives one point. Can the Russian do it? The crowd know the situation and make one big noise. The first serve heading for the backline is not a good tactic. And he blows it.....6-6. Another end change...

Wawrinka 6-3 6-6 *Youzhny
Is this heading for a tie-break? It's 30-30 and Youzhny blazes one long - a waste if I may say. Hold on. I look up again, he challenges the call and it's slapped the line. So much for my pork pies (eyes). He wastes that one though and Wawrinka gets within a point of his hold. A double-fault number three and it's deuce. Oh dear. Youzhny looks to the grey skies as he sends a shocker too long. And then he misses another one. Tie-break time. You weren't thinking of beddy-byes just yet were you?
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Wawrinka* 6-3 5-6 Youzhny
A few more scrappy encounters. A combo of moon balls and harsh slice as they battle the blustery conditions. Hold to love. My instinct says Youzhny is going to pull this match out of the bag. He's got one or two more shots in his locker. But look at the scoreboard I hear you say. Stan still up.
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Wawrinka 6-3 5-5 *Youzhny
Easy hold for Wawrinka. Pressure back on to the Russian.
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Neil at Flushing Meadows, via text 81111: "Desperate times call for desperate measures here. Sitting in the top tier of a very very cold and windy Arthur Ashe court and just had to make the switch from cold weak American beer to strong hot chocolate. Not a decision I made lightly"
Keep us updated on the atmosphere. Many Swiss or Russian fans? Enjoy the drink. No spillage please. Hot chocolate? Deary me.

2206: Thoughts so far? Happy? Frustrated? Hopeful? Talk to me. Tweet me @bbcsport_mark, text me on 81111 (UK) or +44 7786200666 (worldwide) with TENNIS before your message, or get bantering on 606.

Wawrinka* 6-3 4-5 Youzhny
Youzhny does brilliantly to survive the second point with a cracking combo of defence and aggression. 15-15. Youzhny will be mindful that the second set could go against him within a blink of an eye. It's 30-30 and these are nervy times for the Russian. A massive point. Break point. Thwack. Youzhny lifts up his foot and lets rip - a big forehand that is - and it's deuce. Big screams. Oh. How big could that game be? Wawrinka's return drifts long and the Russian fans go bonkers. Good fightback.
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Wawrinka 6-3 4-4 *Youzhny
49 unforced errors and 27 winners so far, the commentators inform us. Wawrinka looks cream-crackered actually. And he plays a loose backhand which takes it to 30-30. A very gentle rally and I'm thinking Wawrinka has not got a chance. Wawrinka opens up his shoulders and a backhand corker gives him a sweet sweet winner. Top drawer and totally unexpected. It goes to deuce as Wawrinka twists around his hips. Signs of early aches? What better word to end a service game than BOOM.
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Wawrinka* 6-3 3-4 Youzhny
The Russian looks strong and races to 40-0 but as the wind rumbles, he chucks down a wide one - double-fault and it's 40-15. Wawrinka has a chance at the net but Youzhny just plops one in at his feet - it's a cracker. Nice hold.
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Wawrinka 6-3 3-3 *Youzhny
Youzhny's footwork looks a little suspect as Wawrinka cruises to a 30-0 lead. Youzhny needs to re-find his weapons. Has he got a date tonight in the Big Apple or something? He looks distracted. Wawrinka dishes up a big plate of top serve and he levels the second set.
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Wawrinka* 6-3 2-3 Youzhny
It's all back to the wonderful world of Mr Topsy-Turvy. The Swiss breaks back. He runs off court and looks fired up. This match is just making me frown. Does anybody have any explanations? The stakes too high? Is the weather playing a factor?
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Wawrinka 6-3 1-3 *Youzhny
Youzhny looks set to take the opening point but Warwinka stoops at the net and claws the ball out from nowhere to stroke the winner away. Nice. I almost got excited about that. That's more like it. Fireworks. Wawrinka charges to the net, Youzhny looks up, charges up his racquet with 3,000 volts of Russian electricity and it's flying back to give him another break.
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Wawrinka* 6-3 1-2 Youzhny
Wawrinka has two break points. A great chance to hit right back in this second set. Youzhny caresses the ball down the line to get one back. It's not enough. Wawrinka grabs his chance.
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Anonymous, via text 81111: " I'm shivering on a golf course, volunteering at a charity event, in the cold, drizzle and rain. U r my only salvation Mark! Go Stan!"
Where the hell are you? It's dark out there. Maybe overseas. Talk to me. Are you OK? Do you need me to dig out the torches for you?

Wawrinka 6-3 0-2 *Youzhny
Youzhny races into the net again and he calmly plants it to within 12 inches of the backline. Sweet stuff. 15-30. And now he's break point. This has come up from no where. Time to crank up the pressure Mikhail. Not like that though. A return flies long and it goes to deuce. And that's the break. Mmmm He needed that. Turning point perhaps?
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2131: Stats so far: 17 unforced errors for Wawrinka - 15 for Youzhny. Warwinka winning 86% of his first serves. handy. Total points won - 40 for Wawrinka, 35 for Youzhny. And two double-faults apiece. I thank you.

Wawrinka* 6-3 0-1 Youzhny
A cheeky backhand off the back foot and Youzhny can only watch as the ball goes flying past his clunky trainers. It goes to deuce and the Russian looks a little wobbly. And the wobble gets even wobblier as he smashes the ball into the net. More break points. Wawrinka's light fluffy fringe blowing in the breeze. Not as strong as yesterday but it's still causing a few problems. Youzhny grabs it by the skin of his teeth but that was hard work.
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2125: My colleague Pranav Soneji has some info on the first set winner. "Swiss-Pole Wawrinka married long-term girlfriend Ilham Vuilloud, a presenter on TSR in Switzerland and former fashion model who is ten years his senior, at the end of last year. Stan become a father for the first time in February earlier this year when Ilham gave birth to a little girl named Alexia. Log on to his website and the first thing that greets you are the words "Stan Wawrinka - Power of Passion". Quite."
Thank you Pranav. Not a lot of passion on view so far.

Wawrinka 6-3 *Youzhny
Wawrinka serving for the set and it's his time to play a loose backhand. 15-30. The unforced errors stats should make for pretty ugly reading in a sec. More errors and it's 30-30. C'mon boys. Sort it out. A sweet gentle cross-court smash at the net gives the Russian break point. It's still all very gentle. Another massive serve again digs the Swiss out of a dingy hole. Deuce. And the Swiss fists are shaking. Wawrinka takes the first set. A strange start to this quarter-final. Remember - winner plays Nadal or Verdasco.
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Wawrinka* 5-3 Youzhny
Youzhny's sporting a peacock blue shirt - he looks ready for a gym workout, black shorts and big black trainers with green piping. It's not a bad look but I've got to be honest - it looks like Mikhail spent 20 minutes digging out his kit at the Lost Property department before the match. A backhand slice to the back and Youzhny charges in - Wawrinka's too good though and belts back the pass. Deuce. It's taken half an hour but both players starting to look a little smoother out there. Both their backhands working up a sweat. ADV to Wawrinka as Youzhny plops a shocker into the net. Big point. Oh lordy. Youzhny's backhand flies wildly out. That's an easy game to give away for free. A stinker.
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Sho_Rahman on Twitter: "Most tentative tennis ever. Both players just floating balls back. Whoever wins this won doesn't stand a chance in semis."

Wawrinka 4-3 *Youzhny
A booming 132mph serves takes the Swiss to 30-15 before he goes off the boil. And an ace gets him out of trouble. Deuce. A real mixed bag in the service department. If this game was a cartoon character - SCRAPPY DO anybody? Another big beautiful boomer and the Swiss nicks it.
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Wawrinka* 3-3 Youzhny
A reminder that Nadal v Verdasco on court at around 0100 BST. Who's staying up? Bit of a flat start to the match as Wawrinka leads 30-15 after a double-fault. Both playing a little gingerly. A few Swiss moon balls in the mix! Very very gentle and then Youzhny fires up a cracker down the line to take it to 30-30. Best point of the match so far. Wawrinka looks like a man who's conserving energy right now. Bit of pitter-patter. The Russian's backhand gets him out of trouble. An early clenched fist and it's honours even.
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Wawrinka 3-2 *Youzhny
Wawrinka wearing a low-key white shirt with a triple-stripe around his back. Not a Friday night going-out shirt but good for a Thursday. Both men are also semi-bearded. My mum wouldn't be happy. Did you know the only time I met Brian Clough he told me off for not having shaved. Another legend and I digress. And that's another hold for Stanislas. Who knows any other Stanislas?
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Wawrinka* 2-2 Youzhny
Another steady service hold. So where are we tonight? Out and about? Snuggled on the sofa? Preparing for school? Still in the office? By the way, Youzhny will be back in the top 10 if he wins tonight - the first time in three years.
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Swiss Miss is London, via text 81111: "I challenge your mystic powers! It will be Wawrinka in four sets, and I dare guess at least 2 sets will go to 12 games"
Check you out and your high and mighty challenges. Can I over-rule that one?

Wawrinka 2-1 *Youzhny
And the smiles get bigger. Wawrinka bags it to love. Is that a serve bagel? Probably not. 11 minutes gone. Already six unforced errors from the Swiss. Three winners though. Fastest serve of the match so far? 131mph by Wawrinka.
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Wawrinka* 1-1 Youzhny
Scrappy service game for Youzhny. So scrappy that he loses it. One break each. Youzhny had a great chance at the net but waves the ball wide. Wawrinka gives a cunning little smile like it was all part of the plan.
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MELTTENNIS on Twitter: " @petenorfolk, beat Johan Andersson 62 62 in 58 mins in the first of his three round-robin quad singles matches at US Open NY."
Yep - great to see Peter back in action playing in the first of his three round-robin quad singles matches.

Wawrinka 0-1 *Youzhny
The Swiss star winds up his serving arm and gets things going. No fireworks and it goes to 30-30 but a third point in a row for the Russian gives him a break point already. A big big serve gets him back in it. Relief for the Swiss fans. Wawrinka makes a rare trip to the net and he blows it. First blood goes to the Russian.
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2039: Not long to go now. Wawrinka to serve. Is Youzhny the favourite? Wawrinka could be a little battle weary. After Murray's win, the Swiss survived five sets to beat Sam Querrey and there have been questions about a leg injury. Will his Swiss pins hold out? Wawrinka said: "It's gonna be difficult for me. I will see how I'm gonna be with my leg and how I can rest for Thursday, but I will be focused more on myself than him." Bring it on. Head-to-heads, it's 2-2. They last played each other in Miami this year, with the Russian coming through 1-6 7-6 (7-5), 7-5. My mystic prediction ball tells me it will be Youzhny in four sets tonight. Dare you question my forecasting powers?

2037: Without further ado. I just wanted to say that for fun. As the US Open reaches a dramatic weekend, I want your thoughts, opinions and banter. I'll be with you for his encounter before Piers Newbery picks up the baton for Nadal. So what are you waiting for? Talk to me... Tweet me @bbcsport_mark, text me on 81111 (UK) or +44 7786200666 (worldwide) with TENNIS before your message, or get bantering on 606.

2036: So here we go. Youzhny vs Wawrinka. They're warming up in the Big Apple which is a 'cool' 21 degrees. How do you see this going? Youzhny is gunning for another semi-final place, four years after making the last-four in New York. Wawrinka is in his first Grand Slam quarter. Did you know that Wawrinka played alongside Roger Federer to win Olympic gold in the doubles in Beijing two years ago? And of course, Wawrinka was the man to snuff out Andy Murray's latest quest for a Slam title a few days ago.

HibaMS on Twitter: "Re:2015 Was gutted, but the great speeches and the generous donation by the Bryan brothers to flood relief have made me happy."

2032: Quick round-up on earlier proceedings. First up today on Arthur Ashe was a storming three-setter semi-final in the women's doubles. Sixth seeds Vania King and Yaroslava Shvedova (USA/KAZ x6) saw off Cara Black-Anastasia Rodionova 6-3 4-6 6-4. Good old tussle that one.

2030: Wawrinka vs Youzhny. The winner plays Nadal or Verdasco in the battle of the Spaniards which is up later. Plenty of action already though to fill you in on. Britain's Laura Robson has sadly made her exit from the junior girls competition at the third-round stage. The 16-year-old eighth seed, a semi-finalist last year, lost 6-3 6-2 to American Robin Anderson. Oliver Golding will be flying the GB flag in the boys doubles a bit later alongside Jiri Vesely.

2028: But you know what? Despite my ramblings, today is not Roger day. That was last night following the smooth and steady demolition of Robin Soderling. Let's move on from Roger if I may. See it like dumping a partner via text. A little cold admittedly, yet swift and efficient. It's because there's another Swiss in town shaking his cow bell. A pretty good one at that. You know the one - the one who saw off the Muzz. Stanislas Wawrinka is taking on the mighty Russian Mikhail Youzhny and there's a semi-final place up for grabs. It's day 11 at the Meadows of Flushing. Are you onboard or what?

2024: As the boys get ready to stroll on to Arthur Ashe, a few thoughts for you. I can't lie to you. Roger Federer has been the most watchable tennis player on this planet in all the days I have walked and bounced around this land they call Earth. There was Beautiful Borg. Magical McEnroe. Sizzling Sampras. Luscious Lendl. Bouncy Boris. And now there's Rousing Rafa edging rapidly towards legendary status. But Fab Feds nicks it for me. Still. Just my opinion. Talk of a mad man? Just wanted to get that off my chest.

2021: It's more men's quarter-final action. Stanislas Wawrinka vs Mikhail Youzhny. Where do you think this one is going?

2015: Congratulations to American pair Liezel Huber and Bob Bryan who have just been crowned mixed doubles champions. They beat Kveta Peschke and Aisam-Ul-Haq Qureshi 6-4 6-4. Quite a few Pakistan fans out there who have been in touch will be gutted. On to the singles drama....