BBC Sport's Piers Newbery Tweeting from the O2 Arena: "Rog obviously very disappointed but remains a gent, and some very sharp dark humour. "I'm happy cos this is my last presser of the year."

1645: Follow all the action as Del Potro and Soderling battle for the right to meet Davydenko in Sunday's final. The second semi gets going from 2045 GMT. BBC Radio Five live sports extra and live text commentary are the places to be. Are you going to be here? Are you? There's nothing else to do this Saturday evening is there? Newsflash - all entertainment venues are closed for the night across the country so that's it - decision made for you. Is the Federer number one status wobbling a little? Many are predicting Del Potro to dominate in the coming seasons. Let's see how he gets on against the mighty Swede later shall we. Another three-setter I am going for. 4-6 6-4 7-6 to Del Potro. There you go. Never say I never stick my neck out. My neck is out and dangling and now I'm open to ridicule. Bring it on from around 2030 GMT.....

tlimvvo2max on 606: "Despite being a big Fed fan I am delighted for Davydenko, who as I've said before must be just about the best player never to make a Slam final - just hope he can win tomorrow, he is a decent guy as well and thoroughly deserves to. But before we draw any larger conclusions from this week, just bear in mind that last year's final was between Davydenko and Djokovic. And the AO final three months later... wasn't. Write off Roger and Rafa at your peril."

BBC Sport's Piers Newbery Tweeting from the O2 Arena: "Bemused faces and lots of rewriting in the media centre. Remember saying 14/1 was worth a punt on NiDav last week. Wish I had believed me."

1638: And the later semi? Henman goes Soderling, Castle goes Del Potro. What do you reckon?

Tim Henman on Davydenko "It looked like he was limited but he's upped the level of his game and now he's a very effective player. He has previously lacked a big weapon to get over the likes of Federers and Nadals to enable him to win a Grand Slam."

Andrew Castle on BBC Two on Davydenko: "This is what happens with brutal hard work. He is a rock and he will not defeat himself. He is a real Russian."

Tim Henman on BBC Two: "Federer will appreciate he didn't play his best. He still got close to winning though. Davydenko has worked incredibly hard and there was even more running today. Fingers crossed he can recharge the batteries. He deserves to be in the final."

1631: One hour 55 minutes of intense tennis. Amazing. Feds is shedding tears as he strolls of the court. Or is that just sweaty eyes? Will Davydenko play Soderling or Del Potro? We will find out later. What a final set. I'd have bet my new house and my pants on Federer coming through that one. Not to be. Brilliant effort to win that. Davydenko says: "Winning my first time against him is amazing for me. I hope I now have some more fans in London."

Federer 2-6 6-4 5-7 Davydenko
Big serving and he's 30-0 up and two points from a stunning win. And then a couple of nervy ones from Davy and Feds gets it back to 30-30. Dear Mr / Mrs ATP - can we make this a five-setter now. This match has turned on its head - brilliant stuff. Davy looking for his first win over Feds in 13. A stunning rally and the crowd are on their feet. A fabulous backhand half-volley and Feds passes Davy to take it to 40-30. More grinding from the grinder and gets match point. DAVYDENKO WINS.

Federer 2-6 6-4 5-6 *Davydenko
Davy looks broken after losing an opening gruelling rally. Feds fists get going again while dejected Davy screams NO (good name for a band that - Dejected Davy). The match is now "intense" says Henman. It's a bit like a fox playing with a small rabbit at the moment - letting the rabbit think he's got a chance of getting away and at the crucial time, the fox gets his paw out and snaps it back on top of the rabbit's head. Does that make sense? But wait - this fox has got slippery paws. Davy has a break point. Where did that come from? And there it is. What a return. Break of serve. I think the fox was wearing a rabbit's mask while the rabbit was wearing his fox costume. Great stuff from Davydenko. He just hangs in there and never gives up. Brilliant. Serving for the match.

Federer* 2-6 6-4 5-5 Davydenko
Feds holds his hand up after taking the first point with the ball flying into the tape and taking a tightrope walk and dropping dead onto the floor. And then it's the point of the match. Davy smashes the ball down and Federer jumps up like a superhero and smashes right back at Davy to take the point. Phenomenal. No superlatives available. Brilliant. (Yeh OK - there's two). Worth it though. What a winner. Two and a half sets of mediocre tennis and he comes up with that. He's edging closer. A challenged line call and it goes 30-30. Big OOOhhhhs from the crowd. This match should be a five-setter. Everybody's just woken up. Davy battles back to edge 40-30 despite Federer recovering with a number of those swipe shots but credit to the Russian. His wife Irina (donned in purple nail varnish) gets on her feet and claps wildly. Brilliant.

Federer 2-6 6-4 5-4 *Davydenko
Feds strolling at 30-0 but an over-stretched Davy digs something out of the bag with a brilliant forehand drive into the body of Feds. All to no avail and Feds has got an almost confident swagger. Almost. The number one is just grinding this one. He's only playing at 70% and it's just enough against a very tired opponent. Perhaps that's the sign of a genius. Perhaps?

Federer* 2-6 6-4 4-4 Davydenko
Pressure winding up for Davy but he eases to the first three points. A quite brilliant rally with Davy breathing fire at the net. Feds is running for everything and is a little unlucky to lob just long after running across from one side of the court to the other. Great energy from the number one. It's another service game for Davy but it's hard work. It's now the "business end" says Tim Henman.

Federer 2-6 6-4 4-3 *Davydenko
Yep, this set is a complete reverse of the first set - stroll in the park for the service game and pushing it close for Davy serve. Feds leads 40-0 but Davy shows there's life in the old dog yet with a sweet sweet pass down the line (along the line? Up the line? - re: the great Piers Newbery 'line' debate from the other day). Brief respite though and Davy has it all to do.

Federer* 2-6 6-4 3-3 Davydenko
Davy wins his service game with just a few swings of his weapon. The arena sounds like a library when he's serving. A crucial game for the match. Can Davy dig in and see off the improving Federer?

nigeweir on 606: "Excellent tennis competition with everyone beating everyone. Even Feds is having to come from behind everytime he plays. Does Davydenko have the mental strength to win the third set. He has always been good and never beat the GOAT yet, and I can not see him doing it today either."

Federer 2-6 6-4 3-2 *Davydenko
"The roles have been reversed" says Tim Henman on BBC Two about this match. Feds wins his service game and looks a tad more relaxed as he heads to his chair. Soderling and Del Potro later. Any thoughts? A bag of fireworks guaranteed. Andrew Castle senses there is a "changing in the guard" in the sport with the likes of Del Potro and Murray challenging Feds for honours. Interesting.

Federer* 2-6 6-4 2-2 Davydenko
Davy's giving it a big push and playing a little more aggressively. Pays off though and he wins his service game without too much work. His legs will be grateful.

Federer 2-6 6-4 2-1 *Davydenko
As well as looking hungrier, quicker and snappier, Federer's serve is tip-top. A lot of Swiss flags being waved about with the smiles having returned to the holders' faces.
* denotes next to serve

Federer* 2-6 6-4 1-1 Davydenko
Good solid comeback from Davydenko. He just needs to settle again because he's not been at the races for about four games.
* denotes next to serve

Federer 2-6 6-4 1-0 *Davydenko
More fist pumping from Feds. The backhand has moved up two gears and the Federer machine is starting to purr.

BulletMonkey on 606: "Glad Federer won that set but I'd like to see Davy beat him finally, especially after the way he played in the first set."

Federer* 2-6 6-4 Davydenko
Federer is starting to find his range. Davy is pulled side to side and his trainers are squeaking on over-time, and Feds takes the opening point. He gets the concrete back in his shoes for the next and it's 15-15. Davy starting to look weary. Two set points. One saved with a big smash (once again aimed at the Swiss). Davy goes wide and Federer screams YES, pumps his first and it's game on.

Federer 2-6 5-4 *Davydenko
Federer eases to 40-15 but then inexcusably punts one down long and wide. And the next point the ball plops into the net - it's deuce. Federer is in one of those pouty moods. He wins the game and strolls off. He knows things aren't going his way but he's still in this match. Andrew Castle on BBC two reveals that Federer last failed to reach a Grand Slam semi-final in 2004. Tim Henman can't remember when Federer last played this badly. If he wins this set though, all will be different.

Federer* 2-6 4-4 Davydenko
Crowd also wake up and with the players strolling back on the court, there are huge screams for "Roger". A stunning swipe shot from Davy helps him to recover and Feds can only put in the net. Can't be nice knowing 98% of the crowd are cheering for your opponent. Feds' head goes down as Davy powers a shot from the net towards his head. We could be eight minutes from game over unless Feds pulls his socks up.

Kalika, via text 81111: "Its technically incorrect to say the is "no tv coverage" of Soderling vs Del Potro as Sky Sports are showing and I am going to watch the match and will b e trying my hardest to get on tele!!!"
Hey good spot. Big apologies. I was seriously wearing my BBC hat there - of course there's TV coverage but on Sky.

Federer 2-6 4-3 *Davydenko
Feds seems to have woken up and plays two beautiful passes to take it to 40-0. Davy wayward and Feds cranks it up.

Federer* 2-6 3-3 Davydenko
It's another quick one. Davy's serve does not let him down and it's back to all-square. Pressure on the Russian there but he handled it well.

Federer 2-6 3-2 *Davydenko
A quick sip of my tea and Feds takes his service game. The crowd sound a little jaded as well. Did the whole of London go out last night and nobody tell me?

Federer* 2-6 2-2 Davydenko
Time for Davy to go a little wobbly. A stray forehand flies long and it's deuce. Federer screams out as he's out-foxed by the Russian after a series of volleys at the net by both players. Quick hands from both but Davy is looking sharp this afternoon. Yep - another cracking rally at deuce and Davy is quicker, Feds looks tired and I'm perking up thanks to a cuppa. What more could you want? A strong serve gives the middle line a big kiss and it's game. Tight stuff.

1513: Don't forget, second semi tonight between Soderling and Del Potro. No TV coverage but BBC Radio Five live sports extra will have all the action. And of course, all live commentary on the web. There's nothing in this world I'd prefer to be doing tonight. Fact.

Federer 2-6 2-1 *Davydenko
Feds drops a beauty over the net but Davy turns on the battery-operated legs and gets to the ball - just - and flicks it across court to leave his opponent a little bewildered. Great feet, great wrists from the Russian. Supercute. Federer hangs on though.

Federer* 2-6 1-1 Davydenko
"Federer's racket is a plank unless you hit it in the middle" says Andrew Castle on BBC Two. Interesting. A sweet rally and Feds is on top until Davy whips in a cross-court top spin pass leaving the Swiss flat-footed. Davy wins it to 30.

Anon, via text 81111: "First set to Davy, but it seems to be Feds habit to give the first set away in this season finale. I'll hold me faith in the main man Fed "

Federer 2-6 1-0 *Davydenko
Federer will want to forget that first set and he comes out looking a little more refreshed and fired up. He looked poor at the start against Murray and came right back in it. Same today? A solid service game though this time.

democracythreat on 606: "Nobody can serve today, it seems. Ni dav to win the title..."

Federer* 2-6 Davydenko
A steady opening rally but Feds hits the tape and before he knows it, Davy's 30-0 up and closing in on the first set. Feds has given up on this set I reckon. Henman and Andrew Castle reckon he was up all night with his kids. Half an hour gone and Davydenko takes it 6-2. Easy really.

Federer 2-5 *Davydenko
And there was me thinking Federer was back on it. He gets broken again by Davy and the Swiss returns to his chair with a huge frown. Top effort from Davy who never gives anything up. The boy's a grinder.
* denotes next to serve

1455: Easy to type 100 words and not add a game to Federer. Sorry about that. It's 2-4 but you knew that.

Federer* 2-4 Davydenko
Another Feds forehand goes sailing wide. "He looks flat and body is lacking energy" adds Tim Henman. A cracking backhand gets him to 30-30 and after a booming rally with at least 25 shots from the baseline Feds take one on the rise and with full top spin Davy has no chance. The world number one looks interested again and he's broken.
* denotes next to serve

Federer 1-4 *Davydenko
Feds continues to wobble. Has his mind started to waver? Perhaps his twins kept him up all night? He will have to "start upping his game", says Tim Henman on BBC Two. Another serve break and Davy steps on the gas.
* denotes next to serve

Federer* 1-3 Davydenko
Davy has steadied the ship in no time at all. What has happened to Feds? The Swiss looked in cruise-control in the opener and then has crumbled. Still early though eh. A quick mention for web only commentary from BBC Radio Five live sports extra.
* denotes next to serve

Federer 1-2 Davydenko*
Couple of sloppy shots from Feds and it goes 30-30. Then hold on - his second double fault in the game and Davy has a sniff. And again! A half-volley forehand dips wildly and it's the first break. Makes life interesting. But I'm not just going to talk like Davydenko is some second rate tennis player. Nadal may not have been fully fit but Davydenko was sensational to beat him a few days ago. Do not write this boy off.
* denotes next to serve

Federer* 1-1 Davydenko
Davy looking a little unsettled. There's 17,000 people glaring down - that's 34,000 eyes. Can't be easy. Plus his legs may be a little wobbly after coming through against Robin Soderling yesterday. Shaky stuff though and his serve will have to improve. Federer's backhand already looks fully primed but then what does he do? He plonks a forehand and then a backhand in the net to take it to deuce. So much for my early superlatives. Another Feds net shot with Davy looking a little more sprightly on his feet. And then game over. All square. Nice.
* denotes next to serve

Federer 1-0* Davydenko
Feds looks stunning in the first point. No, not his navy blue shirt - he pushes Davy to both sides of the court and cracks an easy one past the Russian's backhand. And it's a double boom with two aces and it's first blood to Feds.
* denotes next to serve

1429: Remember in this beautiful crazy multi-media world, there's live video on the web, it's on BBC Two and if you want some words and a little drizzle of interaction then let's get involved here. Feeling good? Got your tennis head? Let's go peeps....they're just warming up and we are 39 seconds way from the start.....

1427: Tim Henman on BBC Two describes Federer as "the artist" while he says Davydenko is a "real fighter".

1424: Federer and Davydenko stroll onto the court. The Russian looks a little nervy - probably a little concerned with the 0-12 head-to-head record he has with the Swiss man.

1420: And of course, I want all your thoughts, all your madness, all your chat about Andy Murray, predictions, any tips for a man with a new shed and tools to go in it. Any challenges I could chuck BBC Sport's Piers Newbery's way. He's down at the O2 so check out his Twitter updates. But today's all about you. How do you get your thoughts in I hear you cry? Text 81111,606 or Twitter

1417: After eight of the 12 round robin clashes have gone to three sets, we're down to the last four players. It's semi-final time. And hey - I've come up with an innovative way of deciding who goes through today without causing too many headaches or forcing the calculators to come out to play. Winner goes through today folks. That's right. The first to two sets. First up today is the mighty Rodge - Roger Federer and he faces Nikolay Davydenko. Should be a cracker. Any predictions? I reckon another three-setter. If I was a betting man I'd go for Davydenko as a useful outside bet. What do you think?

1412: Welcome everybody. Returned from a 24 hour epic house move. My hands are burning, my legs are aching but my heart is screaming "tennis tennis tennis". No Andy Murray I know. We can't do everything for you.

BBC Sport's Piers Newbery Tweeting from the O2 Arena: "Half jubilee line going to upton park, half to O2. Split loyalties but I'm all about roger & co today. Anyway sure zola has it all in hand"

1405: Hello everyone. Welcome to semi-finals day.