Ahead of today's sole practice session the air temperature is 19 degrees C, while the track temperature is 29 degrees. Thankfully, conditions are altogether different to yesterday, with bright sunshine. There's a strong breeze, and a few dark clouds in the distance, but they don't appear to be heading this way. In other words we expect a lot of running this morning as teams make up for the loss of running yesterday and ahead to qualifying and the race.

The McLarens topped the aggregate timesheets, however, it was the pace of the Mercedes, particularly that of Michael Schumacher, that surprised.

Ferrari is clearly struggling for grip, a cause not helped by Massa's off in FP1, while Red Bull has yet to show its hand, Christian Horner revealing that the team has yet to do any low furl running, and by that we mean any this year.

All in all, the mixed weather conditions meant few questions were answered yesterday, today, certainly this afternoon's qualifying session, should be entirely different.

Tyre options this weekend are the medium and soft, though we haven't really seen a lot of either of them thus far this weekend.

Petrov heads the queue at the end of the pitlane, and when the lights go green leads a train of eleven cars out on to the track, including Kobayashi, Hulkenberg, Kovalainen, di Resta, Alonso, Vergne, Massa and Grosjean.

Webber and Vettel are among the early risers, the world champion, like many, performing a practice start at the end of the pitlane.

Advised that he is meant to be 'cold scrubbing' his tyres, Massa replies that his steering wheel feels funny.

The Mercedes duo stay out for a second lap, Rosberg running wide at one stage as does his teammate a few moments later, both incidents taking place at Turn 3.

Of course it wouldn't be F1, particularly a season opener, without controversy, and there is already talk of a potential protest from Lotus and Red Bull, two of several teams concerned by what is thought to be an f-duct device on the Mercedes.

Rosberg gets the session underway proper with a 1:26.982, while teammate Schumacher returns to the pits having flat-spotted his tyre.

As Rosberg eventually heads back to the pits, Petrov, Kobayashi, Hulkenberg, Kovalainen, di Resta and a few others come out to play.

Di Resta's 34.452 indicates the Scot is looking at a high fuel run, while Grosjean goes second with a 28.604, Lotus having done little real running yesterday. Pirelli claims the track is still quite slippery and dusty.

Massa goes fourth (29.381), only to be demoted when Button posts 27.802 to take second. Rosberg remains quickest.

On his first flying lap, Hamilton goes quickest in the first two sectors, and again in S3, crossing the line at 26.620 to go quickest overall. Button's 26.801 makes it a Woking 1-2.

Back on track, Schumacher immediately posts a 26.234, no doubt causing a sharp intake of breath in a few garages along the pitlane. Elsewhere, a spin for Massa, who loses the back end under braking at Turn 15.

A 27.031 sees Webber go fifth while teammate Vettel takes seventh with a 27.668.

As Kobayashi runs wide at Turn 3, which is catching out a lot of drivers, all but Glock, Maldonado and de la Rosa have posted times, 38:30 remaining.

Button complains of a spot on his front tyre, the McLaren driver told to return to base. Rosberg, who goes quickest in S2, is quickest again in S3, crossing the line at 25.929 to go quickest. Mercedes 1-2.

Lotus reveals that the steering on Raikkonen's car has been returned to the original set-up, the Finn unhappy with what the team gave him yesterday.

Senna takes to the grass at Turn 15, the Williams driver losing the backend as he exited the previous corner.

With 33:30 on the clock all twenty-four drivers have posted a time, both HRTs over 9s off the pace. That said, both Force Indias are 7s down on Rosberg as the duo focus on heavy fuel running. Both drivers have completed more laps than anyone else.

Coming up to halftime, it's: Rosberg, Schumacher, Hamilton, Vettel, Button, Webber, Kobayashi, Vergne, Grosjean and Ricciardo. Alonso is twelfth and Massa fifteenth.