Ahead of today's sole free practice session, the air temperature is 21 degrees C, while the track temperature is 18 degrees. Though there was overnight rain, the track is now drying, indeed, the sun is shining. That said, it has been declared a wet session.

As the lights go green, however, up go the umbrellas as a (hopefully) light shower hits the Royal Park.

One of the first out is Heidfeld, who is advised that the rain will last for "about five minutes".

Less than a minute into the session, and there are seventeen cars on track, including Hamilton, who is on inters.

As Barrichello begins a second lap, Kovalainen heads down the pitlane, leaving the Ferraris as the only cars not to appear yet.

Barrichello continues to lap the Autodromo, however, it is only at the fourth attempt that he posts a time (1:40.427). He is joined by Sutil, Piquet, Trulli, Alonso and Glock, who gets it all wrong at the first chicane. Nonetheless, undaunted, Glock soon tops the timesheets (38.261), ahead of Barrichello and Sutil.

Coulthard is informed that most of the drivers are on extreme wets, only a couple on inters. "One-forty is the no-man's land between the two," he is advised.

The first chicane continues to catch drivers out, Alonso being the latest 'victim'.

Much to the obvious frustration of the teams, the rain isn't continuous, its stops and then starts again a few moments later. Nonetheless, Glock raises the benchmark with a 35.712. Alonso is second, ahead of Piquet and Barrichello.

Twenty minutes into the session, Hamilton goes out for another installation lap, returning to the pits, he is replaced, on-track, by his teammate. Massa is also on track now.

Massa goes seventh with a 37.988, as Michael Schumacher looks on (if only!). Glock consolidates his position with a 35.464, while teammate Jarno Trulli goes second.

No sooner has Massa improved to fourth (37.464), than Heidfeld, Nakajima and Vettel all go quicker, knocking him down to seventh.

Vettel goes second with a 36.310, like so many others he is on the extreme wets. Piquet, on inters, gets it wrong at the first chicane and wrecks one of the polystyrene barriers.

Twenty-six minutes into the session, Raikkonen and Hamilton head down the pitlane, both on extreme wets. It is still raining, but nothing like the monsoon we witnessed yesterday.

Raikkonen goes seventeenth (41.164), of seventeen, as Hamilton dives into the pits, the conditions now having suddenly deteriorated. As the World Champion slows, clearly struggling to control his car in the worsening conditions, Rosberg is told; "it's too bad mate, come back in".

With twenty-seven minutes remaining, and three drivers still to post a time, the session comes to a standstill. At several points on the track, most notably Ascari, there is standing water, such is the amount of rain coming down.

It's all academic but the order is: Glock, Vettel, Rosberg, Trulli, Nakajima, Heidfeld, Coulthard, Massa, Alonso and Fisichella.

Twenty-three minutes to go and it stops raining. Heidfeld is advised that there should be no further rain before the end of the session. However, it remains very, very wet out there.

As Heidfeld heads down the pitlane, the first driver to go out, Kubica calls for more downforce. The Pole is advised that other than the standing water, it looks highly likely that this afternoon's session will be similarly affected.

As Heidfeld begins his flying lap, it starts to rain again, at which point Race Control advises that it will continue raining for the rest of the session. Webber, who is also on track, is told to ease off and return to the pits; "it looks a bit scary", says the voice over the radio.

Never mind qualifying, if it continues like this the GP2 race should be sensational, what with the title still up for grabs.

The replay has Nick Heidfeld telling his crew, "I would recommend not to drive in this", says the BMW driver. "If it continues, I think the FIA should consider postponing the qualifying."

Realising that this could well be the way things will remain for the rest of the weekend, Hamilton gets to work. He heads down the pitlane on inters, the only man on track. In the Ferrari garage, even Schumacher is smiling.