Ahead of today's free practice session, the air temperature is 24 degrees C, and the track temperature is 38 degrees. Once again, it is bright and sunny.

As previously reported, Renault has dropped its KERS devices, as has Robert Kubica, leaving just Nick Heidfeld and the McLarens with the controversial systems on their cars this weekend.

Both McLaren drivers have a new interim diffuser, as does Fernando Alonso.

Timo Glock will incur a five-place grid penalty this afternoon after changing the gearbox in his Toyota, while both Red Bulls had limited track time this morning due to a problem with the driveshaft on the Austrian outfit's cars, eventually traced to a faulty seal.

The smart money, as far as today's pole position is concerned, has to be on Jenson Button, however, keep an eye on Jarno Trulli, the Red Bulls and Nico Rosberg.

The lights go green, and Fisichella leads the way, followed by Sutil, Buemi and Rosberg.

The two tyre options this weekend are medium and super-soft, which we will refer to as hard and soft. Surprisingly,

Fisichella appears to be the only driver using softs at this stage, as he crosses the line at 1:39.502 to set the benchmark. However, this is soon beaten by Sutil, Buemi and ultimately Rosberg, who posts 37.646.

Surprisingly, Raikkonen is using the softs, followed, moments later by his Ferrari teammate, also on the softs.

Both Toyotas on track, however, Trulli's 7.518 is almost instantly beaten by Rosberg who improves with a 37.513.

A 37.351 sees Vettel go quickest as attention shifts to the Brawn drivers who are both on track.

Button goes quickest with a 37.31 but again this is almost instantly beaten, this time by Webber, who crosses the line at 37.100. Moments later however, Massa goes even quicker (36.780) before he too is eclipsed by Vettel with a 36.633.

It's fast and furious with the order forever changing. However, with nine minutes remaining it is Hamilton who goes quickest, ahead of Raikkonen, Vettel and Button.

A 36.374 sees Barrichello go quickest, as Alonso heads back to the pits having posted the tenth best time. Webber also dives into the pits but almost does a Rosberg when he goes off into the gravel at the start of the pitlane. Luckily the Australian is able to keep going.

Kovalainen and Piquet are now on track on the softs. The Finn has yet to set a time. Rosberg is also back on track, he too is now running the softs.

As Kovalainen goes seventh (36.646), Trulli, Heidfeld and Glock are all in the danger zone, with Alonso, Webber and Massa hovering.

Heidfeld is back out, but surprisingly still on hards. Either a vary brave move or a dumb one by the German team.

Rosberg goes quickest with a 35.941, having gone quickest in the first and final sectors.