Ahead of today's opening practice session, the air temperature is 29 degrees C, while the track temperature is 28 degrees. It is 18:00 local time and the sun is low in the sky. Following an earlier downfall the track is still damp, indeed, there is standing water on parts of the track, including a couple of corners, consequently the session has been declared wet. Further rain is expected today and for the remainder of the weekend.

At Hispania, Christian Klien is replacing Sakon Yamamoto for the remainder of the weekend, the Japanese youngster having been laid low by food poisoning. Fairuz Fauzy is in Trulli's Lotus this morning while Jerome d'Ambrosio is in di Grassi's Virgin. Also, let's not forget that Nick Heidfeld replaces Pedro de la Rosa at Sauber for the remainder of the season.

A number of teams have brought updates here, most notably Renault, which has a new front wing, as do McLaren and Red Bull, though, in terms of the Milton Keynes outfit, currently only Webber has access to it.

Seven minutes into the session all twenty-four drivers have been out, all of them on intermediates.

Kubica has a rough time of it at the chicane that is Turn 10 - or the Singapore Sling as it is now known.

Twenty minutes into the session, Klien posts the first time of the day (2:18.621). Moments later, Petrov, who is not running the F-duct in this session, posts 2:16.337.

As Petrov improves to 2:09.423, in the Red Bull garage the new front wing is removed from Webber's car and now Vettel has it. However, the Austrian team is eager to point out that it has two of the new wings available, having clearly learned from the problems it encountered earlier in the season.

Schumacher goes second with a 2:09.922 as Petrov ups the ante with a 2:07.277. Buemi is third ahead of Klien (2:11.462).

Schumacher goes quickest with a 2:04.758 as Glock posts 2:05.137 to go second.

Thirty-five minutes into the session, and with apologies to Michael Schumacher, Felipe Massa is the first of the big guns to come out for a second run. As The Brazilian posts 2:06.485 to go fourth, Glock raises the benchmark with a 2:02.180. Barrichello goes third only to be demoted by teammate Hulkenberg (2:05.379).

Nick Heidfeld's first flying lap sees the German go eleventh (of eleven) with a 2:18.898.

Having improved to second (2:02.297), Barrichello complains of rear-locking. Teammate Hulkenberg consolidates third with a 2:02.610.

Currently fourth (2:03.635), Alguersuari looks spectacular as he improves with a 2:00.655 to go quickest. Elsewhere, Heidfeld goes fourth with a 2:02.588.

At half-time, it's: Alguersuari, Glock, Kobayashi, Barrichello, Heidfeld, Hulkenberg, Schumacher, Petrov, Massa and Senna.

As the track improves, Petrov and Kobayashi filly break the two-minute barrier, the Russian going quickest with a 1:59.856.

As Schumacher improves with a 58.504 to go quickest, Kubica heads down the pitlane. Liuzzi goes quickest in S1 finally crossing the line at 59.614 to go third. Kobayashi re-takes the top spot with a 58.025.

With 26:10 on the clock, there are still only fifteen names on the timesheet, with the McLaren and Red Bull duos still to post a time, likewise Alonso, Kubica and Rosberg.

Massa goes third (59.134) despite getting worryingly close to the concrete barriers. Elsewhere, teammate Alonso heads down the pitlane.

Glock is the first driver to make the switch from inters to dry, though there are still damp patches at a number of points on the track. Alonso is also on dry tyres. After a couple of exploratory laps, the Spaniard returns to the pits to change his nose.

With 16:35 on the clock, Hamilton leaves the pits. Elsewhere, Glock takes to the escape road having got it wrong under braking. Kobayashi is still quickest (57.260).

Massa (on inters) improves to second (57.760) having gone quickest in the first sector.

Despite getting very close to the wall in the final corner, Button posts 2:02.373 to go tenth. Hamilton, Webber and Vettel all on track, all on dry tyres.