Ahead of today's sole free practice session, the air temperature is 28 degrees C, while the track temperature is 28 degrees. It's currently not as hot as yesterday and it hasn't been raining constantly like it has on previous days - though there was a downpour a couple of hours ago. The track looks fairly dry, though the new tarmac looks damp, and a few other spots, albeit mostly offline. The session is officially declared wet.

Red Bull set the pace yesterday, with Vettel outpacing his Australian teammate by 0.627s second session. While the five title contenders filled the top five places on the timesheets, Fernando Alonso lost track-time after stalling his car while Lewis Hamilton was over 1.1s off the pace.

Other than the continued concern over the kerbs at the chicane in Turn 10, the big news this morning is that Red Bull have opted to change the engine in Webber's car. At Williams, Nico Hulkenberg faces a five-spot grid demotion after his team changed the gearbox in his car.

McLaren is continuing to run back-to-back tests with its new front wing and older version. As the session gets underway, Hamilton is running the new wing.

The lights go green and Petrov first out, followed by Kubica, Trulli, di Grassi and Glock.

Ten minutes into the session, everyone has been out for an installation lap, indeed, Klien has done two installation laps.

Fifteen minutes into the session, Kobayashi comes out for a second run, followed, shortly after, by di Grassi. While the Sauber driver returns to the pits, the Virgin driver stays out. The Brazilian subsequently posts the first time of the day, crossing the line at 2:00.831.

No sooner has di Grassi improved with a 56.339 than Alguersuari - who looked very good yesterday - posts 54.047. Petrov goes second with a 55.649.

A 52.248 sees Kubica go quickest as the title contenders wait resolutely in their garages. Massa, whose team is still targeting both titles, is on track, the scarlet Ferrari looking gorgeous under the Singapore lighting.

Gorgeous or not, the Ferrari can only manage 53.345, which is good enough for seventh, the Italian team having opted not to use the F-duct today.

A 51.398 sees Schumacher go second as four of the title contender head down the pitlane. Vettel watches and waits.

Schumacher consolidates second with a 50.983 as Massa improves to fourth (51.345). Hulkenberg goes fifth ahead of Alguersuari, Heidfeld and Liuzzi.

Rosberg goes second with a 50.525 while Hamilton, who goes quickest in the final sector, goes tenth overall with a 52.550. Next time around the Englishman runs wide at Turn 5.

The timing screens, which have been playing up all day, have finally lost the plot. Although Schumacher, Hulkenberg and Hamilton all go quickest, Kubica is shown as the pace-setter. The usually reliable live timing app on the iPod also loses the plot.

Anyway, in the real world, Hamilton is quickest on 1:49.000 - as far as the timing screen are concerned it's Kubica on 50.428.

Webber goes second, ahead of Hulkenberg, Vettel, Barrichello, Button, Schumacher, Alonso, Massa and Rosberg.

Alonso improves with a 48.909 to go quickest but he is almost instantly demoted when Vettel posts 48.730.

There's a heart in mouth moment as Kubica almost collects one of the Ferraris which is travelling very slowly as it leaves the pits. Scary.

A number of drivers have run wide at various corners, mostly Turn 5 which is still quite damp.

With 12:45 on the clock, it's: Vettel, Alonso, Hamilton, Webber, Hulkenberg, Massa, Kubica, Sutil, Buemi and Barrichello. Button is eleventh.

Despite the prevailing damp conditions, drivers now start to switch from the prime (medium) tyre to the option (super-soft).

Hamilton (on options) begins a flying lap, however, after just three turns he eases off. Not so Kubica who is very, very aggressive but nonetheless posts a personal best in S1.