Ahead of today's vital qualifying session, the air temperature is 30 degrees C, while the track temperature is also 30 degrees. Conditions remain ideal.

Lewis Hamilton was quickest in this morning's session, with Vettel just 0.277s behind. However, over the course of the three sessions thus far there has been no clear leader, indeed, the Brawn duo, who dominated yesterday's opening session appeared to be struggling this morning, especially in Jenson Button's case.

The Red Bulls have been up there - with Vettel appearing to have the edge over Webber - as have the BMWs, while Ferrari has been disappointing. Both McLaren drivers have looked strong, yes we include Kovalainen, while Force India appears to have lost the pace we saw in Belgium and Italy.

The bad news, as far as Rubens Barrichello's championship hopes are concerned, is that since this morning's session Brawn has opted to change the gearbox in the Brazilian's car. Consequently, Rubens will forfeit five grid places. That said, if anyone can factor this into their strategy, Ross Brawn is your man.

The lights go green, signalling the start of Q1, and Alguersuari leads Fisichella and Sutil out on to the track. Grosjean, another driver to go out early, takes to the escape road after getting it wrong.

As Alguersuari posts the first time of the afternoon (1:50.169), there are 16 cars on track. Fisichella can only manage 51.028 as he continues to struggle with the Ferrari.

As Button begins a flying lap, Buemi goes quickest (49.078) ahead of Raikkonen. Rosberg and Webber are both on hot laps.

Grosjean tells his team that there is "no brake efficiency", "it's alright, don't panic," replies his engineer, "they'll bed in".

Button goes quickest with a 48.632 but within seconds Kovalainen, Vettel and then Barrichello all go quicker. The Brazilian posting a 47.939.

Rosberg posts 47.636 to go quickest as Hamilton goes fastest in the first sector. The Englishman is equally quick in the second sector, finally crossing the line at 47.241 to take the top spot.

Vettel improves to second and Button third as Kovalainen goes quickest in the first sector. The Finn crosses the line at 47.542 to go third, McLaren first and third.

Buemi improves to sixth (47.704), with just over seven minutes remaining, leaving Trulli, Heidfeld, Alguersuari, Grosjean and Liuzzi in the danger zone.

With five minutes remaining just four cars are on track, two of them Ferraris. The Maranello duo are currently fourteenth and fifteenth. Raikkonen goes quickest in the first sector, posting a personal best in the second. At the line it's 47.293 promoting the Finn to second.

With 1:50 on the clock, all but Hamilton and Vettel are on track. Kovalainen making a late decision to go for another run.

Heidfeld improves to third with a 47.347, as Vettel drops to fifth.

A 47.180 sees Button go second as Barrichello posts a personal best in the first sector.