We'll be back for the race at 13:00 UK time tomorrow - will Hamilton back up pole position with victory? It's all to play for. Join us then!
Follow the Spanish Grand Prix live with Eurosport. The race starts at 13:00 on 12 May 2012. Find race results, standings, stats, scores and track info. Keep up with the top F1 drivers and teams including Lewis Hamilton (Mercedes), Valteri Bottas (Mercedes) and Max Verstappen (Red Bull Racing).
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It looked like ending in anti-climax, but in the end it was a thrilling finish. Hamilton shone, an outsider in Maldonado on the front row - something for the Spanish to cheer with Alonso in third... remarkable.
The top 10 - Hamilton, Maldonado, Alonso, Grosjean, Raikkonen, Perez, Rosberg, Vettel, Schumacher, Kobayashi.
Hamilton has come to a stop halfway through his follow-up lap, and that's prompted ironic cheers from the Spanish crowd.
Vettel's seen enough - he doesn't complete his lap because he knows he won't figure in the race.
1:21.7 FROM HAMILTON! SENSATIONAL! HALF A SECOND CLEAR!
Grosjean on second - MALDONADO IS ON POLE - WHAT ABOUT HAMILTON?
Raikkonen can't beat it - he's second - Perez slots third....
Alonso sets 1:22.302 - it's roars in Spain - good enough for pole!
Alonso is going well, Raikkonen and Grosjean both in front of Hamilton's mark...
The strange situation is that only two drivers are on the board so far - but eight drivers will race for pole now - with Kobayashi missing out because he ran out of fuel and Schumacher not going for a timed lap.
Vettel is going to go out again. There's a sense that 1:22.5 is decent but very beatable.
Rosberg sits second, about four-tenths down on Hamilton, who's coming out again. Maldonado on new tyres as well - and he's got every chance of claiming pole today. One lap to get it right.
Here comes Alonso - he's on new tyres, as is Raikkonen. It's about time. We could yet have a grand-stand finish...
Rosberg looks as if he'll actually be trying to compete with Hamilton's time, but this is not much of a spectacle so far, is it?
Four drivers have been out - Schumacher sets sector times and hits the pits.
Hamilton lays down a proper time - a 1:22.560. It's marginally slower than his lap in the previous sector - but he's the only man who has a lap time on the board so far.
And in fact he doesn't send a complete lap, coming into the pits. Do Red Bull think they can put Vettel on pole?
Hamilton comes out to the track, which has dropped about 5C in temperature. Vettel is only coasting so far. He's making no effort to set a competitive time - just to get on the board.
Vettel waited for more than a minute there to get out right away - trying to steal a march on his rivals as a cloud threatens overhead. Any loss of track temperature could play into his hands.
The final session begins - time to find out who will be on pole. Vettel left it late to get out in the first two sessions but he's waiting at the exit of the pit lane to get going this time around.
Webber was told not to run again after that time - but his 1:22.9 wasn't good enough. It's a remarkable situation. We have Williams, McLaren, Lotus, Sauber, Ferrari, Mercedes and Red Bull in the top 10 shoot-out, and right now any one of them on pole would be no great surprise.
What do you think will happen? Join me on Twitter @Mark_Eurosport and let me know.
I thought Lewis Hamilton had shown himself to be a shoo-in for pole with that 1:22.4 - and then Maldonado beat it by three-tenths of a second. The Lotuses are in good shape too, and this one is wide open onfce again.
Eliminated from Q2: Button, Webber, di Resta, Hulkenberg, Vergne, Ricciardo, Massa.
Remarkable! Maldonado turned up at the death and looked like a pro to go top - Perez struck late too, although he's just pulled up halfway around the track - has he run out of fuel?
Webber fearing the worst, he'lll have to step it up - Perez goes third! Maldonado posts an incredible 1:22.105 - Button is out of the top 10 too!
TIME UP - COMPLETE YOUR LAPS...
Vettel comes through in fifth on a 1:22.8 - and that's more than enough - Button and Rosberg 9th and 10th - can Button improve? He's back up to sixth...
Alonso surges up to fourth, which pushes Massa straight back out of the top 10 - Di Resta shoots into sixth, so Button, Rosberg and Vettel are in need of some times here.
Only drivers in the pits are Hamilton and Webber. They both feel they've done enough - but it's going to be a real scrap in the next coupel of minutes. Massa is desperately trying to break into the top 10 - it looks like he will, but will he then be displaced?
Raikkonen four-tenths adrift in second place, Grosjean then goes faster than his team-mate with a 1:22.667. Lotus confirm they are a factor in the race for pole - but has anyone got what it takes to beat Hamilton to pole?
Raikkonen on a par with Hamilton in sector one, but that has been where the Lotus have enjoyed their best pace. He's two-tenths down by sector two.. Grosjean perhaps a touch quicker though...
Lotus have yet to post times in this session and they are dark horses this weekend. Massa is out of the top 10 in 12th, sandwiched by both Force Indias.
Top 10 as it stands: Hamilton, Webber, Button, Rosberg, Vettel, Schumacher, Alonso, Perez, Maldonado, Kobayashi
Wow - Hamilton puts down a 1:22.465 - that's miles ahead of the field. That should be enough to see him through. Webber slots into second half a second adrift, but it's Hamilton who's laid down the gauntlet here.
Button top with a 1:23.3, straight away knocking Rosberg off the top of the standings.
Now just the Toro Rossos who are yet to head out on track.
The first man to set a marker willbe Kobayashi, however - he locks up at the end of the second split but he's through to post a 1:24.031.
The Mercedes follow, before the McLarens and the Ferraris join the track. And here come the Red Bulls...
A Sauber breaks ranks and takes to the track - it's Kobayashi. Di Resta follows, as does Perez. Senna is back in the pits and talking to his engineers.
Another game of cat and mouse to start of this session - nobody out for a lap so far.
Interesting point from Red Ears in the comments section: "9 of the last 10 SGP's have been won from pole. Anyone content to sit out Q3 to save tires for tomorrow's race had better be content to finish where they qualify today" - the other factor is that with the midfield so tightly-bunched, strategies will be harder to implement and get drivers out safely ahead of traffic.
A quarter of an hour on the clock for Q2 - 17 cars will become 10 by the end of the session.
1.1 seconds between 1st and 17th, by the way. Expect some big names to fall by the wayside in Q2.
So has that left you any clearer about who'll start from pole position tomorrow? Let me know your thoughts and predictions for the race on Twitter @Mark_Eurosport
Karthikeyan was outside the 107% mark compared to Hamilton's time. So as it stands he won't be starting tomorrow.
SESSION OVER - Drivers completing their final laps, but not Senna, who lost his line at 12 and 13 and slid into the gravel. He'll start in 18th, and joins Petrov, Kovalainen, Pic, Glock, de la Rosa and Karthikeyan in elimination.
1:22.583 for Hamilton - very nice, but it took another set of tyres to confirm his place at the top. It's all over to Senna - can he get ahead of Vergne - it's going to be close... HE'S OFF!
Hamilton is now down to 15th - just as well he's out on track! Looks as if he'll go back to the top, however.
Vergne into 17th, and he's in some trouble. Senna in 18th, but he's started his first sector poorly...
Alonso safely through into second, Massa slots in 10th, then Rosberg leaps into third. Plenty of shuffling here, and none of the drivers appear entirely confident that they have done enough.
Raikkonen slots into second, Webber to third, and then Grosjean tops them all. Hamilton and McLaren must be nervous - he's going out on the soft tyres.
Vettel is through into second, but half a second down on Maldonado on the same tyres. Red Bull don't look too happy with that.
The drivers are out and they're going for soft tyres - here's Alonso, and here are the Red Bulls about to begin their flying laps. Button on a soft tyre too.
'MASSIVE understeer' says Jenson Button to his race engineer. Not sure it would be a race weekend without Button worrying about understeer, mind.
Maldonado slices through on the option tyres - the first man to do so - and he shows the difference that compound offers by coming in six-tenths quicker than anyone else. Webber and Vettel look set to do one tour on the soft tyres.
Drivers able to shave some time off their laps with another lap on the hards - Schumacher up to third, Hamilton dips just under 1:24 with a 1:23.989.
Top 10 as the drivers prepare for a second run: Hamilton, Perez, Alonso, Grosjean, Raikkonen, Schumacher, Button, Rosberg, Massa, Senna. Neither Red Bull has been out yet.
Button yet to post a time - but once he does it's only good enough for 7th, half a second off the pace.
Plenty of movement now - the Sauber of Perez goes top by a tenth, then Lewis Hamilton shaves another tenth off that.
Nothing blistering so far - Alonso posts a 1:24.3 to head to the top of the standings, half a second up on Rosberg, another two-tenths clear of Grosjean.
To put that into some context, McLaren have told Lewis Hamilton that they estimate a 1:24.0 will be good enough to be safe.
Di Resta is going to post the first lap, though expect it to leave plenty of room for improvement. He's held up by the Marussia going into the final corners and has to settle for 1:25.615.
Hard and soft compound tyres available to the drivers this weekend - a two-compound gap, with the mediums left out this weekend. Everyone seems to have gone for the hard so far.
Yes, here they come - Raikkonen out on track, and much to the delight of his home crowd, here is Fernando Alonso.
I hear some revving! Paul di Resta breaks cover four minutes into the session. Romain Grosjean follows him. There you go - expect the others to follow suit...
The top drivers will be hoping to use just one set of tyres in this session and save compounds for Q3 and the race. Not even a back-marker ready to have a go.
It's 29C and sunny in Barcelona today - 41C on the track. But nobody is rushing out just yet...
The excitement is... well, not quite there yet. No action yet as drivers wait for the track to clear up.
Away we go! 20 minutes on the clock, bottom seven drivers to be eliminated.
If you need a quick refresher course on the Circuit de Catalunya in the five minutes before Q1 starts, it's not too late. Here's everything you need to know.
A little bit of housekeeping - this is the circuit where the teams do most of their testing these days - so if any circuit gives the chance for the teams to iron out the kinks and work with an established set-up, this is it. Red Bull boss Christian Horner reckons any of nine drivers could end up on pole today, while Mark Webber, last year's polesitter, has a bit of a head cold but is apparently absolutely fine to compete.
And to finish the warm-ups, this morning defending champion Sebastian Vettel was top of the pile. So, in summary, it's wide open.
In the afternoon, Ferrari had slipped well down the pecking order and it was McLaren and Jenson Button who were top of the timesheets.
There's been little predicting this season so far - but if you're looking for clues from practice, here's what we know. Alonso set the fastest time in FP1.
Good afternoon everyone and welcome to LIVE updates from qualifying for the Spanish GP in Catalunya!