Half-an-hour before today's all-important qualifying session, it is bright and sunny. However, this is Malaysia and as we know from experience the weather can - and often does - change in a heartbeat. One minute it's bright and sunny, next we're hit with a deluge that brings everything to a standstill, witness last year's race.

Every day for the last week the weather has changed round about this time, and with last year's embarrassment still fresh in the organizer's minds a few basic precautions have already been taken.

For a start off, this session and the race have both been moved forward by an hour, thereby, should the worst happen, giving us a slightly bigger window rather than having to end the race prematurely due to failing light

Furthermore, should today's session be completely washed out, the organizers have plans in place for qualifying to be held tomorrow morning. However, that would be a last resort, for if today's session were unable to continue beyond Q2, the grid would be based on the positions at the end of Q1. Similarly if the session has to be stopped in Q3 the grid would reflect the order at the end of Q2.

Lewis Hamilton set the pace in both of yesterday's sessions while in today's session he was pipped by Mark Webber in the final moments. The Red Bull appears to have the advantage, however, there remains that massive question mark in terms of reliability. Indeed, following an engine failure yesterday afternoon, the Australian was running a new powerplant this morning.

As ever, it is the usual suspects that dominate - Red Bull, McLaren, Ferrari and Mercedes - but the battle behind them is almost as fascinating, though Williams appears to be lagging behind thus far this weekend.

With five minutes to go before the lights go green the rain begins to fall, and how. The air temperature is 31 degrees C, while the track temperature is 33 degrees. Humidity is 60 percent.

Knowing that the session could be stopped at any time, the drivers will be keen to establish themselves right from the outset and post a banker lap. Williams claim that the current downpour will last for around fifteen minutes then clear up. They also claim that this is as bad as it will get. We shall see.

The lights go green and Kamui Kobayashi leads a train of ten cars all shod with Intermediates. Vettel in the only one of the big guns to go out early, a brave move by the German or a reckless gamble?

As Petrov spins at Turn 2 it is noticeable that some parts of the track are totally dry, hence the need for Inters.

Buemi posts the benchmark time, the Swiss crossing the line at 48.945. de la Rosa and Kobayashi make it a Sauber 2-3 only to be split when Vettel posts 50.466 to go third.

A 47.520 sees Kubica go quickest as Buemi takes to the grass. Still no sign of the seven remaining big guns who wait resolutely in their garages.

As de la Rosa goes quickest (47.153), Schumacher leaves the Mercedes garage and heads down the pitlane on Inters. The German is followed by Alonso and the McLarens.

Kubica raises the benchmark with a 46.283, as all but di Grassi are on track.