Ahead of today's sole free practice session, the air temperature is 26 degrees C, while the track temperature is 30 degrees.

Reading the British mainstream media this morning you'd be forgiven for thinking that McLaren, and particularly Jenson Button, has this in the bag, the British team and its driver having apparently overcome its grip problems and left the opposition for dead.

On the other hand, one might be of the opinion that McLaren faces an uphill battle here this weekend and that it is Red Bull and, to a slightly lesser extent, Lotus, that have the edge.

Mercedes has yet to truly show its hand this weekend, and while Ferrari was quickest in yesterday morning's session talk of the team already considering putting its resources behind its 2013 car give cause for great concern.

Once again tyres appear to be the deciding factor, though there are clearly a few chassis that are hurting here for a number of reasons.

Other than the gap between the two tyres on offer, hard and soft, what is also interesting is that it is believed temperatures will drop by as much as 10 degrees on Sunday.

Back to tyres, and it is interesting to note that more and more people (fans) appear to agree with Michael Schumacher in terms of how much contemporary racing relies on those four bits of rubber. At a time when there are fears that running in Q3 today could be minimal - as drivers attempt to save rubber - one has to wonder whether the sport has taken a step too far.

The lights go green and Kobayashi leads Kovalainen and Vergne on to the track followed by Ricciardo, Karthikeyan, Grosjean and Petrov. Karthikeyan, who car was driven by Dani Clos in yesterday morning's session, completed just one lap in the afternoon before his car conked out leaving the Indian very, very frustrated.

Four minutes into the session all but Hulkenberg and the McLarens have been out for an installation lap.

As Hamilton, the last driver to appear, returns from his installation lap, Alonso heads out for a second such lap.

After a few minutes of total inactivity, Pic heads down the pitlane in the Marussia. Shortly after he is joined by Raikkonen and Petrov.

As Pic and Raikkonen begin the first flying laps of the day, more and more drivers pour on to the track including Webber.

Pic crosses the line at 28.495 however, attention switches to Grosjean who has ground to a halt just before Turn 10. "Engine stalled, engine stalled, what happened," he asks. His team advise that there is a fuel pressure issue. A bitter early blow for the Enstone outfit,

Ricciardo posts a 27.907 to go quickest, rivals laps having been compromised by the yellow flags that followed Grosjean's stop.

Rosberg raises the bar with a 25.158 but Perez and Raikkonen are both on hot laps. The Finn posts 25.362 while Perez blast straight to the top of the timesheets with a 24.554.

A 24.689 sees Maldonado go second as Hamilton falls foul of the traffic problems here, the Englishman subsequently running wide in Turn 3 after going over the marbles that litter the outside of the track.

With 33:00 on the clock, as Hamilton goes third with a 24.907, all but Grosjean, Vettel, Massa, Alonso and Button have posted times.

Another improvement from Maldonado sees the Williams driver close to within 0.017s of Perez.

As Vergne makes a late, late dive into the pitlane, Vettel goes seventh (24.967) and Button fourteenth (25.903).

Rosberg is the first driver to make the switch to the softer option tyres, the German currently fifth.

Alonso goes third with a 24.730, as McLaren has a new steering wheel for Hamilton.

Vettel takes third from Alonso with a 24.628, closing to within 0.074s of Perez.

Predictably, Rosberg posts a PB in S1, and again in S2. At the line the German posts 24.070 to go quickest, the Mercedes only really fast in that final sector. Elsewhere, Massa complains of poor grip levels.