Ahead of today's opening practice session the air temperature is 19 degrees C, whilst the track temperature is 21 degrees. It's wet, it's very wet. It's been wet for some time and looks likely to remain so.

Tyre choices this weekend are hard and medium, though we won't be seeing much of those this morning. Also, there is just one DRS zone and that's on the main pit straight.

There is only one reserve driver on duty, Jolyon Palmer in Romain Grosjean's Lotus.

Whilst today and tomorrow are due to be wet, we are currently expecting it to be dry on Sunday. Which could be fun.

The big question is whether Singapore was merely a 'blip' for Mercedes, however, it's unlikely we're going to discover much in these conditions.

Despite the rain, the enthusiasm of the fans isn't dampened, far from it, the stands have more spectators than some of the newer additions to the calendar have on race day.

The lights go green but there is a distinct lack of activity. The fans sit and wait patiently.

Ericsson gets things underway, the Swede heading out in the updated Sauber. He is followed by Kvyat, who is warned of 'rivers' at turns 4, 7 and 12.

Massa, Bottas, Ricciardo and Vettel also venture out. Everyone is on full wets.

"Something is wrong with the steering," reports Hulkenberg, "it goes light then heavy, it is not consistent."

"Do not take any risks, there's a lot of standing water," Maldonado is warned. It's asking for trouble.

With Stevens, Rossi and Hamilton yet to appear, Kvyat is the first driver out for a second run. When he reports that his brakes are not working very well, he is told to be "more positive". "The brakes are good," he responds.

The Manors finally appear, leaving Hamilton as the only 'no show'.

Nineteen minutes in and Hamilton finally heads down the pitlane. The Briton is clearly up for it, hanging out the rear end of the Mercedes at a couple of corners.

No sooner has Hamilton returned to the pits than teammate Rosberg ventures out for another exploratory lap and a subsequent practice start.

The opening half-hour, when drivers usually have access to a free set of tyres, comes to a close with no times on the doors.

"Team discussing on the radio how much running to do in these conditions," reveals Mercedes. "Depends on Sunday's weather!"

Alonso looks set to post the first time of the days, but after two tantalisingly quick sectors he dives into the pits.

Hulkenberg venture out and towards the end of the lap he is told to drive through the pits for a launch. He duly obliges and then returns to the pits.

Asked about track conditions, Vettel says "there appears to be more rain around 12, 13 and 14 compared to the start/finish straight".

Having said the "track is quite grippy", Verstappen has a big moment in T12. He subsequently posts the first time of the weekend, 1:51.741. Moments later, Sainz goes exactly two seconds slower. Raikkonen subsequently splits the pair with a 53.527.

As Verstappen improves to 51.640, Rosberg posts 52.849 to go fourth, before improving to 51.117. Vettel posts 52.773 to go fifth.

The Williams duo are the first to try the Inters, as Vettel complains of a "lot of wheel slip".

His time (55.761) and difficulty in controlling the car, suggests that Inters are not quite the order of the day yet. Elsewhere, Vettel posts 51.270 to go second.

Bottas runs wide at the infamous 130R.