Ahead of today's sole free practice session, the air temperature is 27 degrees C, while the track temperature is 29 degrees. Humidity is 84 percent.

While it had been bright and sunny for much of the morning, around twenty minutes before the start of the session it began to rain. Not too much but it is clearly in the air with some big dark clouds in the distance. We know from experience that while sometime we can escape with a quick downpour that dries out in no time, we can also suffer a deluge of Monsoon proportions.

Other than that, the big excitement here has been a fire which has badly damaged part of the Lotus team's hospitality suite. Thankfully nobody was hurt but the team has had to make alternative arrangements for its guests.

Lewis Hamilton set the pace in both of yesterday's sessions, the McLaren looking comfortable on both the hard and medium compounds. While Melbourne winner Jenson Button was up there, so too were the Mercedes duo and Sebastian Vettel, even if the mood in the Red Bull camp is more than a little down at present.

The big question is tyre degradation, something which the powers that be called for in order to improve the show, and which they appear to have here in spades. Indeed, in terms of degradation there is little between the two compounds, leading to Pirelli suggesting that we could be seeing some teams adopt a four stop strategy on Sunday.

"Malaysia is one of the biggest challenges that we will face all year, and that is down to the nature of the track and the weather," says Paul Hembery. "We can expect a similar performance gap between the two nominated compounds as we saw in Australia, however, our target is still for that gap to be less than one second - even though there is a whole step missing between the soft and the hard compounds that we have chosen for the race.

"Tyre strategy is going to be very important," he adds, "particularly when it comes to looking after tyres at the beginning of a stint."

The world champion described his car as undriveable, while Webber has had all manner of changes made to his car in an effort to lessen tyre wear. In fact, other than the McLarens, one of the few other teams that appears to be getting the best out of its rubber is Ferrari, whilst Mercedes quietly admits concern.

The dusty track surface has led to a number of offs and excursions, with Paul di Resta having fun and games in both yesterday's sessions.

Sauber is having a reoccurrence of the gearbox problems that plagued it in Australia, while a change of gearbox means a five-place grid penalty for Lotus' Kimi Raikkonen.

Minutes before the start of the session, Rosberg is standing outside his garage looking anxious, his Mercedes thought to have a n engine problem, though at this stage it's not known how serious it is. Judging be the German's face, it's fairly serious.

The lights go green and Glock leads the way, followed by Vergne, Ricciardo, Kobayashi, Perez and a host of others. With the session declared wet, intermediates are the order of the day. Since the rain has stopped and the heat and wind are already drying the track we expect that it won't be too long before the drivers switch to slicks. Assuming there are no more downpours.

Schumacher reports that it is dry, and the overhead shot confirms this.

Within minutes all have been out except Rosberg, di Resta subsequently coming out for a second installation lap.

While the track does indeed appear to be dry, there remains the threat of rain, particularly this afternoon. All of which complicates things in terms of qualifying and the race, the drivers preferring things to be one way or the other not in between.

Fifteen minutes into the session, as his rivals wait patiently, Rosberg is the last driver to come out, the German performing a practice start which he aborts and then tries again, this time with success. Senna is also on track.

The Brazilian is the first driver to post a time, the Williams crossing the line at 1:43.721. Back in the pitlane his rivals watch with great interest. All except Pic and de la Rosa who head down the pitlane.

Senna improves to 42.276 as Alonso heads down the pitlane. While the track appears bone dry, there are clear droplets of water on the camera lens on the Ferrari and a few suspect damp patches in the final sector.

As Senna posts 41.329 and Pic 57.918, Alonso splits the pair with a 43.907. Elsewhere, teammate Massa gets to work.