Ahead of today's practice session the air temperature is 19 degrees C, whilst the track temperature is 21 degrees. Needless to say it is still raining, but despite the fact the track won't be open to spectators for another two hours this session is going ahead.

Such are the conditions, Inters cannot be used until further notice warns Race Control.

While we are not sure how much, if any, running there will be, should qualifying not happen, which is a possibility, the grid could be decided on this afternoon's times.

The lights go green and Ricciardo leads the way, followed by Ericsson, Maldonado and Grosjean.

Though he's treading very gingerly, Ricciardo looks likely to be the first driver to post a time. Indeed, he subsequently crosses the line at 2:12.758. remember, this could be for pole.

More and more drivers pour on t ot the track, among them Vettel, Raikkonen and the Mercedes duo.

Raikkonen is told the rain "may increase in five minutes, so early laps will count". Elsewhere, Hamilton spins and Rosberg is off in the gravel having damaged his front wing.

Bottas goes quickest with a 2:03.234, ahead of Kvyat, and Massa.

A 2:03.280 sees Vettel go second as Rosberg heads back to the pits.

No mistakes this time for Hamilton who goes quickest with a 2:02.561. However, Vettel hits back with a 2:01.441.

"It's not as bad as I thought," says Ricciardo. "On extremes there is aquaplaning, but it's safe enough to run."

No sooner has Raikkonen posted 2:00.785 to go quickest than Vettel responds with a 2:00.380. A Ferrari 1-2.

"Rain is getting heavier," warns Vettel. "A lot of aquaplaning in the first sector," adds his teammate after a major wobble. A big moment for Verstappen also.

Last to go out are the Manors, which seems odd considering that anything is possible in these conditions.

As Ericsson gets horribly out of shape, Hulkenberg improves to third with a 2:01.503. Elsewhere, a moment for Massa.

Eighteen minutes in and all but Rosberg have posted a time. However, the German is back on track.

Ricciardo is warned that conditions are worsening as Massa is told the best conditions are "now and for the next five minutes".

Nasr is a passenger as his Sauber aquaplanes down the hill and off in to the gravel.

Bottas leapfrogs Hulkenberg to take third, as Massa complains "this is getting difficult".

On his first timed lap Rosberg posts 2:01.474 to go fifth, one place ahead of his teammate.

Hulkenberg improves to second with a 2:00.496, with Bottas taking third moments later.

Hamilton is back on track as opinions on conditions remain divided.

Unsure why he is still on old tyres, Alonso is told that he needs to keep two sets for qualifying and the race, each driver allowed just three sets.

No problems for Hamilton who goes quickest in the first two sectors, finally crossing the line at 1:59.517 to go quickest.

Vettel goes off and over the grass at T18 but is able to continue. Shortly after he has another moment, this time at T9, and is left to roll backwards down the hill before turning around. "If you ask me conditions are getting quite bad," he says. "I keep spinning."

As Perez spins, more and more drivers head back to the comfort, and safety, of their garages. "I feel more rain, more aquaplaning," says the Mexican.

After another big moment, Bottas heads back into the pits, leaving only Hulkenberg, Ricciardo and Rosberg on track. The Australian subsequently pits however.

"Conditions are really bad," Rosberg is told, "so bring it back in and look after the car."