Ahead of this afternoon's session, the air temperature is 21 degrees C, while the track temperature is 37 degrees. It remains bright and sunny, however, there are dark clouds in the distance and talk of rain before the session concludes.

Fernando Alonso topped the timesheets this morning, ahead of Vettel, Kubica, Webber, Massa, Schumacher, Hamilton and Button. Tyre options are medium (prime) and super-soft (option), though we saw little of the softer tyre this morning.

The lights go green but it is over a minute before Senna heads down the pitlane to get the session underway. The Brazilian, whose Uncle won here six times, is followed by Glock, Chandhok and Hulkenberg.

Senna posts 25.830 but this is soon beaten by Glock who crosses the line at 24.742.

Hulkenberg goes quickest with a 22.044 but Hamilton is already on track as is Webber. The Englishman crosses the line at 20.193 as Webber goes quickest in the first sector. The Australian posts 20.037 to go quickest but this is beaten by Barrichello and then Hamilton (18.690).

Glock gets it all wrong at Ste Devote as Alguersuari goes second only to be demoted by Kubica who posts 18.757.

The times tumble as driver after driver improves on Hamilton's 18.690, indeed, within the space of a minute six drivers have gone quicker. Once the dust has settled, Liuzzi is quickest (17.537), ahead of Hulkenberg.

Button goes third with a 17.699 and immediately complains that his car is "too pointy". Moments later, Vettel goes quickest with a 16.856 while Webber makes it a Red Bull 1-2 with a 17.025.

A 16.563 sees Schumacher split the Milton Keynes cars, as Kubica goes quickest in the first two sectors eventually crossing the line at 16.101.

Such is the speed with which the timesheets are changing it's difficult to keep up. Webber takes the top spot from Kubica but the Pole soon takes it back with a 15.935. Still no sign of the option tyre.

Alonso is one of several drivers pushing ever harder, getting closes and close to the barriers. The Spaniard somehow keeping it all together and taking third with a 16.186, ahead of Sutil, Schumacher and Vettel.

Thirty five minutes into the session both Ferraris are on track, on the option tyre and on hot laps. Massa goes quickest with a 15.585 but is soon eclipsed by his teammate who posts 15.435.

Next time around, Massa lap is destroyed by di Grassi, however, Alonso encounters no such problem and crosses the line at 14.904.

A 15.013 sees Rosberg split the Ferraris as Hamilton gets it wrong at Anthony Noghes, thereby screwing the end of one lap and the start of the next.

Sutil and Schumacher are both on track, both on the option tyre. The Mercedes driver goes fourth with a 15.143 while the Force India driver posts 15.460 to go sixth.

Webber is now on track on the option tyre, however, his first sector is relatively poor, indeed, the entire lap is well off the pace. Clearly the Australian isn't going for a time but merely trying the option tyres on a heavy fuel load, much like they'll run at the beginning of Sunday's race. Teammate Vettel, also on the option tyre, improves to sixth with a 15.455.

With thirty-five minutes remaining, Rosberg is warned that rain is expected within the next five minutes. Moments later, Alguersuari has a hairy moment at the Nouvelle Chicane as the first drops begin to fall.

Despite the first few drops of rain beginning to fall, Vettel improves to third with a 15.099.

Kovalainen gets out of shape at Rascasse and almost clout Massa, however, it is unclear whether the incident was really the fault of the Ferrari driver who appeared to deliberately slow the Finn. Next time around, Massa tries something similar with Glock.

Replay shows Schumacher locking up and missing the Nouvelle Chicane. The German remains fifth quickest, ahead of Hamilton, Kubica, Sutil, Button and Webber.

With just under twenty minutes remaining, Buemi has done the most laps (34), ahead of Vettel, Massa and Hulkenberg who have all completed 32 laps. Kubica is quickest through the speed-trap ahead of Petrov, Hamilton, Liuzzi and Sutil.