Ahead of today's first practice session, the air temperature is 19 degrees C while the track temperature is 17 degrees. It is bright and sunny, absolutely perfect weather.

Almost all of the teams have updates here this weekend, while the FIA has opted to hold off on its plans to introduce a rule aimed at preventing teams from changing their engine mapping which was being done in order to create more downforce. In yesterday's press conference, Mark Webber, quite rightly, suggested that the FIA appears to change the rules almost by the hour.

When the lights go green Kovalainen leads the way, followed by Ricciardo, Karthikeyan, d'Ambrosio and Kobayashi.

Hamilton and Webber are amongst the early risers, the McLaren one of the most heavily updated cars here.

Tyres available this weekend are hard and soft, Pirelli introducing a new harder compound hard tyre.

Five minutes into the session all but Maldonado have been out, Williams not wanting to run both its drivers at the same time.

Massa is the first driver to post a time (1:47.387), Ferrari continuing to make full use of these Friday sessions. Shortly after, Schumacher posts a 33.513, the German told not to use his DRS on the main straight.

Fifteen minutes into the session, the Saubers go quickest, Perez posting 29.577 and Kobayashi 29.995. Karthikeyan can only manage 37.360.

As Perez improves with a 27.512, Hamilton is on track however, he aborts his lap telling his crew that "something is not quite right" with his car. Though he is told to pit, the Englishman continues and goes second with a 27.948.

Glock is running very slowly, the German watched by an anxious Jerome d'Ambrosio from the pitwall. Elsewhere, Karthikeyan improves with a 33.302 to go fourth.

A 31.958 sees Maldonado go fifth, while Button takes fourth with a 29.318. Next time around the Englishman improves with a 27.516 to go second.

Alonso complains that the track is very slippery, grip level being very low. Meanwhile, teammate Massa goes sixth with a 29.896.

On his first flying lap, Webber goes quickest in the second sector. The Australian maintains his pace in the final sector also, crossing the line at 27.075. On his next lap the Red Bull driver ups the ante with a 25.743.

As Schumacher begins a run the German is warned of the strong tailwind on the main straight. Tailwind or not, Webber improves with a 25.142 as teammate Vettel goes eighth with a 28.606.

As Alonso begins his first proper run of the day, Vettel goes second with a 26.600. Elsewhere, a massive lock-up for Alguersuari. The Spaniard needs a decent result here this weekend what with teammate Buemi improving race by race and Ricciardo waiting in the wings.

At half-time, it's: Webber, Vettel, Rosberg, Button, Alonso, Perez, Schumacher, Hamilton, Maldonado and Hulkenberg.

Alonso splits the Red Bulls with a 26.480 as Heidfeld goes eighth. Teammate Petrov has yet to post a time. The Russian, having had a brief chat with Jackie Stewart, climbs into his Renault.

Hamilton improves to fourth with a 26.988, however a 26.379 from Rosberg sees the McLaren driver demoted to fifth.

Another early bath for Maldonado who goes off into the gravel at Turn 14 after losing the rear end of the car. In the Williams garage team boss Frank Williams looks suitably unimpressed. Thankfully, the Venezuelan didn't hit the barriers, the gravel having done its job.

Vettel is told not to use his KERS as Petrov complains that his tyres feel "like ice".

Early days but the Lotus duo is surprisingly off the pace, both over 4s shy of Webber's time.

In the McLaren garage the mechanics are working furiously on the rear of Hamilton's car, the Englishman having only completed 11 laps thus far.

"We need boost, boost, boost," Rosberg is told. The German is currently third, 1.237s off Webber's pace.