1420: Time for me to bid you elveda and point you in the direction of bbc.co.uk/f1, where you can read Sarah Holt's report and watch various pieces of excellent video. More clips and interviews will appear throughout the day. The third and final free practice session runs from 0900-1000 on Saturday and is live on the BBC Red Button, the BBC Sport website and BBC Radio 5 live sports extra. Then comes qualifying from 1200-1300 and that's live from 1100 on BBC Two, the Red Button and online. Radio commentary courtesy of 5 live sports extra once again. I'll be back in position to kick things off at 0830 on Saturday. A special weekend awaits.

Rated_Lolo on Twitter: "This could be a major turning point for Mercedes, while in stark contrast Ferrari's problems go on."

Quemerford on Twitter: "Great job from Paul Di Resta, in front of Sutil again. A real star."

Red Bull Racing on Twitter: "Mark was fifth fastest in FP2, while Seb had to watch from the garage as his car was being repaired. Roll on Saturday."

1358: Most of the teams and drivers will be pleased with their running in FP2 - aside from Red Bull and Sebastian Vettel. Arguably the last driver you'd expect to see finishing rock bottom of the timesheets, Vettel was made to pay for heading out on intermediate tyres in pouring rain during FP1. The reigning world champion and current points leader mounted a kerb at the exit to Turn Eight, aquaplaned into the grass and rammed his car into a wall. While everyone else enjoyed the dry afternoon conditions, Vettel was consigned to the Red Bull garage as mechanics worked to repair his badly damaged vehicle. The German has it all to do on Saturday if he is to maintain his 100% record in 2011 qualifying and then win his third race of the season come Sunday.

Force India on Twitter: "Session complete with both our guys in the top ten! Paul ends the day P8 and Adrian in P10."

1345: Rosberg's team-mate Michael Schumacher was 0.607 seconds off the pace in fourth, with Red Bull's Mark Webber (1:27.149) fifth and Felipe Massa of Ferrari (1:27.340) completing the top six. Renault's Vitaly Petrov (1:27.517), Paul di Resta of Force India (1:27.725), Sauber's Sergio Perez (1:27.844) and Di Resta's team-mate Adrian Sutil (1:28.052) all make the top 10. Britain's Di Resta outperforms Sutil yet again.

Press Association F1 correspondent Ian Parkes on Twitter: "A fine session for McLaren who finish 1st and 3rd, sandwiching the Mercedes of Nico Rosberg. Lewis Hamilton's caution of yesterday may well be misplaced."

1335: So Button is the top dog thanks to that lap of one minute 26.456 seconds. The Englishman pips Nico Rosberg of Mercedes by 0.065 seconds, with Button's McLaren team-mate Lewis Hamilton (1:27.003) third fastest. The top three completed 26, 29 and 31 laps respectively to make up for a first practice session on Friday morning that was heavily disrupted by rain.

1330: And Jenson Button holds on to finish with the quickest time in the second free practice session for Sunday's Turkish Grand Prix. Good job, McLaren.

1328: Up front, Jenson Button is the man to beat. The 2009 world champions sits top of the pile with a 1:26.456. He's 0.065 seconds clear of Nico Rosberg and 0.577 seconds ahead of Lewis Hamilton. Miachel Schumacher and Mark Webber are also in the top five.

1326: Pastor Maldonado of Williams has taken more spins than a carousel wheel today. He loses grip for the umpteenth time shortly before the end of the session and finally bites the dust, his car crane-lifted off the track and taken by lorry back to the pits. He'll be looking for significant improvement on Saturday.

BBC Sport's Andrew Benson: "Re Mercedes, there's no doubt that, after a pretty disappointing time in the first two races of the season, they bounced back in style in China, with Nico Rosberg leading for about a third of the race. He dropped down to fifth towards the end because he had to save fuel. I don't think it's realistic to think Mercedes can win in Turkey - and I don't think the team think they can either given a straightforward race. But they are looking like they can mix it pretty close to the front given the right set of circumstances."

mhafiz91 on Twitter: "Mercedes are looking in good shape… could they be the dark horses in Sunday's race?"

1319: TV replays are showing just how bumpy it is at the end of the long back-straight leading into Turn 12. The incredibly heavy braking required to slow down into that corner has caused the tarmac to crumple up like a carpet and it's literally making the cars jump up and down. That long straight (from Turns 10 to 12) is where the Drag Reduction System zone will be deployed in Sunday's race. For any newcomers out there, the Drag Reduction System (DRS) is an overtaking aid. It lets drivers open their rear wing at a designated point on the track as they seek to pass an opponent.

Inside Ferrari on Twitter: "Fernando is back on track. It was not an easy session for him... Now he is running on soft tyres."

1308: Press Association F1 correspondent Ian Parkes reports via Twitter that Alonso was indeed suffering from a hydraulics issue.

BBC Sport's Sarah Holt in Istanbul: "Paul di Resta has been linked with a seat at Mercedes in 2012. The Scot's start in F1 has drawn high praise from Mercedes vice-president of motorsport Norbert Haug, and the pair are often seen together on the F1 circuit. 'You are always interested that teams like that are interested in you,' said the rookie. 'I definitely would like to be in the position of that one day. But at the same time I'm fully focused on doing my best job for Force India. I'll continue eyes forward as there is still a lot up for grabs.' Di Resta won the 2010 German Touring Car Championship (DTM) title for Mercedes and the Scot paid his dues by attending the first DTM race of 2011 in Hockenheim last weekend. Was it a bit strange to be back in his old stomping ground, I wondered? 'I suppose it was because I'm not defending my title. There were a lot of people I didn't get round to thanking and then it was straight into a new era of my life. But I've done three F1 grands prix and I'm enjoying myself here.'"

1305: Another strong showing from Britain's Paul di Resta today. The Force India driver finds himself ninth on the timesheets with a fastest time of 1:28.007. Shaken not stirred. Talking of Di Resta...

1300: Alonso manages to get going again by his afternoon takes another turn for the worse as he comes to a halt on entering the pit lane. Ferrari mechanics scurry out of the garage to rescue their man.

Andy, London, via text on 81111: "It sounded like something was not sounding right with his engine as Alonso turned in - you can clearly hear it."

Calum, Stockport, via text on 81111: "The engine or gearbox of Alonso's car sounded very rough before he spun."

1250: Fernando Alonso takes a spin at Turn Six. Not sure how that happened - it's a relatively easy left-hander. Maurice Hamilton on BBC Radio 5 live sports extra questions whether it's another hydraulics problem for Ferrari... there was certainly a lack of grip as Alonso lost control of his rear tyres.

1248: And Rosberg becomes the first driver to dip under 1:27 seconds this weekend. The German posts a 1:26.961 to lead Vitaly Petrov by 0.556 seconds, with Rosberg's team-mate Michael Schumacher in third. Mercedes in good form.

1244: We tune into Ferrari's team radio to hear Felipe Massa complaining of "big problems" with his brakes. More on that as and when we get it, but the Brazilian doesn't look overly troubled. He's currently fourth fastest with a lap of 1:27.959, which is 0.607 seconds off the top time set by Nico Rosberg at the head of the field.

1242: And here's a bit more from Pirelli's motorsport director Paul Hembery: "Turkey is one of the most important events of the year for us, as we have had our production facility at Izmit for more than 50 years now. As well as hosting some very important guests this weekend, we're also looking forward to what should be a spectacular race on a stunning circuit. Istanbul Park should provide the tyres with one of their toughest tests of the year, because of the high-speed corners, abrasive and bumpy surfaces, and huge forces that act on the cars. The fearsome reputation of Turn Eight is in every way justified, and this should contribute to relatively high levels of tyre wear. I expect us to see three pit stops per car, but of course it will depend on the individual strategies that the teams choose to adopt, which have become an important feature of the races so far. While temperatures in Turkey are normally warm, the initial forecasts that we have received suggest slightly cooler conditions than usual, so I think we're all in for another very intriguing and exciting weekend."

1240: Tyre supplier Pirelli have once again nominated the hard 'prime' and soft 'option' rubbers this weekend. They've also brought a new evolution of the hard compound for all the teams to try out during Friday practice, as was the case in Malaysia. Pirelli's research and development director Maurizio Boiocchi says: "We're looking forward to seeing our new evolution of the hard compound tyre on track in Turkey on Friday. At Pirelli, we don't believe in standing still so, in collaboration with the teams, we're always working on new evolutions of the tyres that we hope will benefit the sport throughout the year. If we see the results that we expect from this life-sized test of the new tyre, our aim will be to use it at the next race in Barcelona. This tyre will provide less degradation and so we expect it to last longer, but the warm-up time will also be a little longer and there will be less grip."

ChrisD_Bingley on Twitter: "What tires are teams running on?"
From what I can see, most of the drivers are using the hard 'prime' compounds. More on tyres in a moment.

1230: No sign of Fernando Alonso at present. Ferrari have just tweeted to say their mechanics are checking "something on the hydraulic system on Fernando's car".

BBC Sport's Sarah Holt in Istanbul: "McLaren are cracking on after opting to take a rest during a miserable first session, when neither Lewis Hamilton nor Jenson Button set a time. The team say there is nothing to worry about; they just didn't want to waste their limited tyre supply. Each team are allocated just three sets of wet tyres and four intermediate sets per race weekend. McLaren say they are hoping to run through some of their updates this afternoon and get a run on the soft tyres."

1228: The pendulum swings from McLaren to Mercedes as Nico Rosberg leaps atop the timesheets and then sees team-mate Michael Schumacher bump him into second place. Button, Hamilton and Vitaly Petrov of Renault complete the top five.

1220: The drying track is allowing teams to put their upgrades to the test and McLaren are beginning to shine. Jenson Button tops the timesheets with a lap of one minute, 28.222 seconds and Lewis Hamilton is second fastest with a 1:28.245. Both men have completed seven laps so far in FP2 after barely even getting out the garage in FP1.

Team Lotus on Twitter: "Now the weather has improved we can better evaluate new parts. We have some new suspension components and new brake ducts on the cars here."

David Herron, Washington, via text on 81111: "Do you think Sebastian Vettel's new haircut is a sign of intent that he is looking for a new drive after all? It is silly season and he no longer fits the profile of the archetypal long-haired skater-boy Red Bull driver. Mark Webber has always had short hair and look at the problems he's had with the team over the years!"
One of the more outlandish suggestions, I must say.

1210: Just to remind you, this is a 90-minute session that you can watch live on the BBC Red Button and right here on the BBC Sport website, while audio is available through BBC Radio 5 live sports extra. However, you can of course take things at step further by getting involve with our coverage via the Twitter hashtag #BBCF1 or text to 81111 if you're in the UK. If you want a specific question answered, pop me a tweet @bbcsport_david and we'll do our best to get back to you.

BBC Sport's Sarah Holt in Istanbul: "It's that time of the year when the rumours start circulating about driver moves for 2012. Mark Webber opened his media session in Turkey by saying: 'Right-o, next year. Let's get it out of the way in August, next question.' The Red Bull driver wasn't going to get off that lightly though. 'We haven't had too many discussions as yet but in the next few months things will start,' Webber went on when pressed. 'I'm in good contact with the team and we realise how many good things we've done together. Whether it ends this year or I go again next year, it doesn't depend on results; it depends on how I feel.' The 34-year-old Australian signed a new one-year deal with Red Bull at last year's Spanish Grand Prix - which is next up on the calendar - but he said this time it would 'probably be longer'. He also added that it was 'unlikely' he would join another team."

BBC weatherman Ian Ferguson on Twitter: "The rain has been steadily clearing eastward, as evident on radar loop, so improving conditions now."

1200: Hmmm, anything but ideal preparation for Vettel and Red Bull. The sun's coming out and it looks as though his rivals are going to get some really good running out there in FP2. Green lights signal the start of the session and several cars come straight out to get installation laps under their belts.

BBC Sport's Sarah Holt in Turkey: "I've been down to Red Bull and it looks as if Sebastian Vettel, who crashed heavily in first practice at the daunting Turn Eight, will not be able to take part in this afternoon's second session. Red Bull say they are trying to get his badly damaged car ready but they don't expect to be able to manage it. And the eagle-eyed Lee McKenzie has spotted Vettel walking around in jeans."

1157: And here's a bit more from Holty...

1154: BBC F1 pit-lane reporter Lee McKenzie has an update on Sebastian Vettel. Lee's Tweeted to say: "Just seen Vettel running around in jeans, no overalls 10 mins before session. Looking unlikely he'll run in FP2 after crash in FP1."

Alice, medical student in Oxford, via text on 81111: "Never have I cycled home from the dissection room so fast as today to catch FP2!"

Team Lotus technical chief Mike Gascoyne on Twitter: "Looks like the rain has stopped and a dry line is appearing on the track. Forecast now saying it may stay dry for the rest of the weekend."

1150: Anyway, less of the doom and gloom - we had enough of that in a rain-ravaged first free practice session earlier today. The skies are clearing and we're all set for what should be a fascinating FP2.

1140: Forgive me for starting on such a bleak note, but that's the stark reality facing Turkish motorsport and the resplendent Istanbul Park circuit. It really is a cracking track, one which the drivers insist is among the most challenging and exciting all season. Since 2005 it has played host to some truly unforgettable races and equally memorable incidents - but this could be the last weekend it features on the F1 calendar unless a compromise can be reached.

1130: Are we about to witness the last-ever Friday practice session for the Turkish Grand Prix? Its six-year contract expires after Sunday's race and if reports are to be believed, that deal is unlikely to be renewed. We'd better enjoy it while it lasts...

1015: Right then, high time for a short break. I'll be back to bring you live coverage of FP2 at 1200 but in the meantime keep your eyes across bbc.co.uk/f1 for Sarah Holt's report from FP1, Friday's gossip column and plenty more besides. It was a morning that should have belonged to Fernando Alonso - but will be remembered for Sebastian Vettel's spin and crash.Istanbul Park has never been a happy hunting ground for the German - he has two more practice sessions, qualifying and Sunday's race to put that right.

Pirelli_Media on Twitter: "FP1 over, Alonso quickest on a drying track. The rain has stopped falling but conditions are unlikely to dry completely before FP2 at 2pm."

any_shaped_ball on Twitter: "Alonso fastest in practice - wonder if he can kickstart his season in Istanbul. We'll see tomorrow..."

SuaveMick46 on Twitter: "Viva Fernando!!!"

MastrEcko on Twitter: "Upgrades, rain, aquaplaning and crashes. F1; back with a bang."

0950: So, Fernando Alonso takes the spoils in the first free practice session for Sunday's Turkish Grand Prix. But given the unrelenting rainfall we've had this morning, the timesheets are pretty meaningless. For the record, Alonso was quickest for Ferrari with a lap of one minute, 38.670 seconds. Mercedes driver Nico Rosberg was 1.402 seconds off the pace and team-mate Michael Schumacher was third with an effort of 1:40.330. Sebastien Buemi of Toro Rosso completed the most laps (22), while McLaren's Lewis Hamilton failed to set a time and Sebastian Vettel spun his Red Bull into a fence as his exited the high-speed triple-apex bend at Turn Eight. Action-packed but not a particularly pleasant session for the drivers.

BBC pit-lane reporter Ted Kravitz: "The McLaren mechanics sent Lewis out in plenty of time to get a practice start in, but the clutch was sticking and Lewis had 10 seconds trying to get it engaged and that is why he missed the red light."

0930: McLaren belatedly join the party and it looks like they'll just be asking Hamilton and Button to get practice starts under their belts... although Hamilton seems to have a problem... he's struggling to engage the clutch on exiting the pit lane and he's come to a halt... the McLaren crew sprint to his rescue and that certainly was not on the agenda. A bad morning for both championship leader Sebastian Vettel and second-place Lewis Hamilton.

0927: Twenty drivers have put in timed laps now - but still no sign of Hamilton or Button. Alonso leads the way from Rosberg, Schumacher, Heidfeld and Petrov. And here's another yellow flag... it's Schumacher... not for the first time he's aquaplaned at Turn 11.

0925: Red Bull's resident tweeter reports that Vettel "spun off after getting on to the kerb [at the exit of Turn Eight]. It's a right ice rink out there."

BBC pit-lane reporter Ted Kravitz: "Amongst all the miserable faces in the Red Bull garage there was one that was pretty neutral. It was an Australian, good-looking, with a big chin - Mark Webber at the back of his garage as he surveyed the scene with his race engineer."

0920: Vettel trudges back to the pits cutting a fairly disgruntled figure. Meanwhile, his rivals return to the track with 10 minutes left in this rain-affected session. Fernando Alonso tops the timesheets with a lap of 1:38.670 on the wet tyres - he's not going to make the mistake Vettel did by heading out on inters. Sixteen drivers have now set timed laps - but neither Lewis Hamilton or Jenson Button are among them.

0915: The Red Bull is lifted away as a flurry of marshals run around clearing debris from the track. Terrible start to the weekend for Vettel and I'd be intrigued to hear your thoughts on that smash. Get in touch with me via the Twitter hashtag #BBCF1 or a direct Tweet @bbcsport_david and I'll endeavour to publish the best comments. You can also text us on 81111 if you're in the UK.

0910: Vettel tells his engineers via the Red Bull team radio that "there was some water on the exit. There was nothing I could do."

BBC F1 commentator Martin Brundle on Twitter: "Vettel has just shunted big time at T8. He's ok. They are all struggling with standing water but he touched artificial grass to begin spin."

0905: Bad news for Sebastian Vettel. The German comes out on intermediate tyres and completely loses control exiting the famous Turn Eight, aquaplaning before careering into the grass and mashing his Red Bull against a safety fence. The RED FLAGS are out and we're set for a little delay.

BBC Sport's Sarah Holt in Istanbul: "Sergio Perez has been holidaying in Houston, Texas but sadly he didn't get time to visit Nasa's space centre before he cut his vacation short to return to work with Sauber. One thing the dedicated Mexican rookie doesn't want to miss out on is winning his first points at Istanbul Park, a track he is familiar with from his GP2 days. 'It's important for me to be back at a track that I know. It's part of [my confidence] but so is my progress in F1. I'm very happy so far.' Perez was named by BBC commentator Martin Brundle as his pick of the drivers at the opening race in Australia when he finished seventh only for Sauber to be disqualified from the event because of a technical infringement. Sauber are trying out some mechanical updates and changes to the rear of their car but plan their major upgrade for Barcelona."

0857: Only 15 of the 24 drivers have set timed laps so far and the others - including reigning world champion and current points leader Sebastian Vettel - may be kicking themselves because the rain appears to be coming down harder and harder. Another man yet to hit the timesheets is Sergio Perez of Sauber...

0855: A couple of drivers have now aquaplaned at Turn 11, which features in the middle of the long back-straight between Turns 10 and 12. Come Sunday, that'll be the only place where we'll see use of the Drag Reduction System. There's free use of the DRS in practice and qualifying, although the wet weather means it can't be deployed at present for safety reasons.

0850: Meanwhile, Nico Rosberg leapfrogs Alonso atop the timesheets with a 1:40.072. He's in fine form, the German. Kamui Kobayashi , Alonso, Michael Schumacher and Vitaly Petrov complete the top five.

0845: Narain Karthikeyan has been telling Natalie Pinkham of the problem that forced him on to the grass at the start of the session. "I think they found some data which was not right and they just wanted me to shut down the engine," says the Indian. "It was more preventative than anything I don't think we have damaged anything."

0840: Fernando Alonso knocks Buemi off top spot with a 1:40.897 on wet tyres. Big weekend for Ferrari after their early-season woe. Chatting to the media on Thursday, Alonso insisted his team would made a step forward having failed to get a driver on the podium at any of the three races to date. "We have some new parts here and in the next races," said the Spaniard. "It's an improvement but it's not a revolution. We will not improve the car completely in one race. Step-by-step we are trying to close the gap."

0837: Finally we're seeing some laps posted to the timesheets. Seba Buemi leads the way with an effort of one minute 41:306 seconds.

Force India on Twitter: "Install laps complete for both cars on wet tyres. Paul is evaluating a new front wing during this session."

Ferrari on Twitter: "Good morning from Istanbul Park, where springtime has still to come... it's raining and it's very cold: it looks like a winter test :-)"

Williams F1 on Twitter: "Too wet to evaluate the new aero parts this session, new front wing and rear wing will go on if it it's dry later on."

0828: Seems like the rain is getting heavier. Cagoules at the ready. Wet tyres all round from what I can see.

Virgin Racing CEO Graham Lowdon: "We have a very large upgrade package; we needed to move the car forward quite a bit. It's a really front-to-back change. Visually the car is very different. There's a complete new floor, a higher nose, and the aero treatment at back is different. We're also running slightly different specifications on each car, but the wet weather is getting in the way a bit. [Ultimately] we want to gain well over a second."

0825: A period of calm is broken as Lewis Hamilton roars out for an installation lap before returning to the pits. McLaren are among the teams bringing fairly significant upgrades to Turkey this weekend - and another are Virgin Racing...

BBC Sport's Sarah Holt in Istanbul: "Paul di Resta has made an impressive start to his Formula 1 career, winning two points for Force India in his first two races and narrowly finishing out of the points last time out in China. But the 25-year-old Scottish rookie is entering unknown territory in Turkey. 'I've not driven on this track at all,' explained Di Resta. 'Normally I don't take too long to learn a track, but the weather looks tricky and you've got to understand that you're going against guys who've had umpteen races at these tracks. You just have to be patient but any experience I can get will be a benefit. It's all becoming more natural to me and hopefully I'll be battling for some more points this weekend.'"

0820: For what it's worth, I'd throw Ferrari's Felipe Massa into the mix. The Brazilian is the most successful driver at the Turkish Grand Prix with three wins in the five years this race has been staged.

BBC Sport pit-lane reporter Ted Kravitz: "I'd like to raise Jenson Button as a dark horse for winning here this weekend. He's finished first and second in the past two years, and loves this track."

0815: Quite tricky to see who's who on the track at present, what with all the spray flying up from the tyres. Some of the drivers are on wets, others on intermediates. We're yet to see any timed laps and Maurice Hamilton on 5 live sports extra explains that the teams will be pretty frustrated by this weather because all the upgrades they've brought with them this weekend need to be tested in dry weather. "'They'll learn absolutely nothing right now".

0805: Not a great start for Hispania's Narain Karthikeyan as he comes to a halt on the grass. He's asked on the team radio if it's an engine problem and the Indian replies "I stopped it, I stopped it". Natalie Pinkham is on the case.

0800: The sight of green lights and the sound of screeching engines can only mean one thing... Turkish Grand Prix weekend is officially GO, GO, GO!

BBC weatherman Ian Ferguson on Twitter: "Outbreaks of rain Friday morning, tracking east. Noticeably cool; 12-13C. Current radar suggests heavier pulses of rain at times. Saturday likely to remain dry; sunny spells; 15C. Sunday cloudier; mostly dry but showers possible; rather cool again; 14C. "

BBC Radio 5 live pit-lane reporter Natalie Pinkham: "It's cold and it's wet - and it's been officially declared wet by Charlie Whiting, which means the teams can use their wet tyres. Air temperature is 10 degrees and track temperature a mere 11."

0755: Wind, rain and gloomy skies have made for a thoroughly miserable start at Istanbul Park but one man who seems in high spirits is Nico Rosberg, who's just been spotted doing keepy-uppies with an old-school back-and-white panelled football in the Mercedes garage.

0750: Both sessions can be seen live on the BBC Red Button and right here online. Digital radio users can also access commentary via BBC Radio 5 live sports extra. Happy?

0745: Pretty straightforward drill today. Free practice one kicks off at 0800 and goes on for 90 minutes. We then break for two-and-a-half hours before FP2 at 1200 - and that's also a 90-minute shindig.

0740: Holty will be in position all weekend to bring us the very latest from the 'Otodrom'. She'll be feeding straight into this live text commentary but be sure to follow her Twitter too. And our fellow F1 expert Andrew Benson for that matter. You'll be hearing from him a bit later, I'm sure.

BBC Sport's Sarah Holt in Istanbul: "Hello again. After nearly three weeks since the last time we met in China, the European leg of the Formula 1 season has begun in Istanbul - although, yes, strictly speaking we are on the Asian side of the cross-continental city. There have been 'hilarious' references at BBC HQ of F1 going 'Cold Turkey' because it is surprisingly chilly here and it's been spitting with rain for much of the morning. The cold and damp conditions mean it will be more difficult for teams to gauge whether the updates they have brought to Turkey will add any performance to their cars and, if the rain continues, then limited wet running so far this season means there is still plenty to learn about tyre performance too. Toro Rosso reserve Daniel Ricciardo - who is in for Sebastien Buemi in this session - described the miserable weather as 'a shame' and told me he expected to do an installation lap on extreme wet tyres and switch to intermediates later."

0730: Istanbul Park, Turkey, and the resumption of hostilities after a three-week hibernation. Formula 1 is back. Start your engines.