Ahead of today’s sole free practice session, the air temperature is 22 degrees C, while the track temperature is 29 degrees. It is bright and sunny.

There was drama early this morning when Williams suffered a KERS-related fire to Pastor Maldonado’s car however, the team is confident that everything is under control.

Sebastian Vettel was quickest in yesterday afternoon’s session, when the option tyres came into play, while Hamilton led the way in the morning.

Changes to the tyres have not yet changed the order as much as some were expecting, then again, it is very early days. Certainly, while Red Bull has the edge here, Mercedes pace appears genuine.

Lotus is hoping for warmer conditions whilst dropping its passive DRS ‘device’, while Ferrari is still struggling, not helped by an ECU problem that side-lined Alonso yesterday morning.

McLaren is looking a little stronger, and actually appeared to have an edge on Force India here.

What was interesting yesterday was the dramatic drop-off on in terms of the soft (option) tyres. The prime tyre is the medium, both of which now feature the Kevlar belt as opposed to the steel version Pirelli had been using.

The lights go green and within seconds there are thirteen drivers on track, di Resta leading the way. All, including the Ferrari duo, and Maldonado, are on the prime rubber.

Rosberg is told that there is a tail-wind going into turns one and seven. The first corner caught out a number of drivers yesterday.

While most drivers return to their garages, Perez stays out and posts the first time of the day (1:34.382).

No sooner has Perez got down to 33.684, than Rosberg posts 31.911, the German immediately on the pace.

Rosberg improves with a 31.618 as Button goes second (32.704) ahead of Perez, Pic and Van der Garde.

A mistake by Grosjean as he leaves the pits forces Chilton off track but no harm done. Hamilton also appears to be struggling, the Englishman running wide at T2. Nonetheless, next time around he goes second with a 32.118.

Raikkonen and Grosjean go third and fourth as Vettel and Webber finally leave the pits. Still no sign of the Ferrari duo since the installation laps.

Having posted a 36.287 on his first lap, Vettel goes quickest in the first two sectors next time around, finally crossing the line at 31.365 to go straight to the top of the pack. Moments later Webber posts 31.792 to go third. Game on.

After twenty minutes, all but the Ferrari duo have posted times.

Told that Rosberg is suffering understeer, Hamilton complains that he has huge oversteer. Elsewhere, Maldonado has a problem, although running very slowly he runs wide and into the gravel in T7.

Vettel improves to 21.294 and Webber 31.298 as Red Bull establishes itself at the top of the table, the pair separated by just 0.004s.

Back in the pits Hamilton complains that his car is “so unstable at the rear”. Meanwhile, Alonso and Massa are finally on track.

Alonso goes eighth with a 32.585 while Massa posts 32.792 to go twelfth.

At half-time, it’s: Vettel, Webber, Rosberg, Grosjean, Hamilton, Raikkonen, Hulkenberg, Alonso, Ricciardo and Button.

Bianchi, who pulled out of yesterday afternoon’s session with a stomach bug, has completed 11 laps but remains 5.530s off Vettel’s pace at the foot of the timesheet.

In the Sauber garage, Hulkenberg gets a new nose while further down (up?) the pitlane mechanics are working on Raikkonen’s car.

The FIA’s Jo Bauer walks the pitlane to check that everyone is abiding the new tyre ‘rules’. The rules being in inverted commas because, according to our sources, yesterday’s dictat from Charlie Whiting is not enforceable.