Ahead of today's sole free practice session, the air temperature is 15 degrees C, while the track temperature is 25 degrees. It is overcast and unusually cool however, it is also fairly windy.

No surprise that Sebastian Vettel led the way in both sessions yesterday however, what is surprising is the reaction of sections of the media to the fact that the McLarens were both within 0.247s. Fact is, Vettel was on a heavy fuel load when he posted his fastest time and clearly has lots more in reserve.

The Mercedes were both up there - as was the case in Friday practice in Malaysia - as were the Renaults - despite two offs for Nick Heidfeld - while a hydraulics problem compromised Fernando Alonso's track time. Paul di Resta didn't run in the second session due to a fuel pressure problem however, he will be buoyed by the fact that teammate Sutil finished seventh quickest.

Both Hispanias finished ahead of the Virgins, Glock losing track time due to a mechanical problem in the first session and an engine problem in the second.

Tyre options this weekend are the same as in the first two races, hard (prime) and soft (option). Of particular interest was the fact that Lewis Hamilton complained that his soft tyres were going off after one hot lap yesterday while rivals were able to get two hot laps.

Also, while Pirelli claim that some drivers will only need to make one stop on Sunday, many drivers believe that as in Malaysia there will be three or more stops.

Di Resta is ready and waiting at the end of the pitlane as the lights go green, the Scot - who is celebrating his 25th birthday today - followed by Liuzzi, Kobayashi, Alguersuari, Petrov, Buemi and Vettel.

Just three minutes into the session, everyone has been out - unusually busy today.

Schumacher complains that the brakes as "pulling to one side", his crew confirms that the left hand side is running a little hot.

Thirteen minutes into the session, di Resta is the first driver to come out for a second run. Karthikeyan follows.

The Scot crosses the line at 1:40.459, losing time in the final sector as the DRS kicks in. Karthikeyan posts a 45.509.

No sooner has di Resta raised the benchmark with a 39.710 than Schumacher posts 38.516. Glock goes third ahead of Karthikeyan and Liuzzi. As the German improves to 38.345, Perez posts 41.047 goes third (41.047). Di Resta complains of low grip between Turns 8 and 9.

Barrichello goes fourth and Rosberg fifth, but all eyes on the McLaren duo and Vettel who are all on track.

Button goes quickest with a 37.367 as Button posts 37.622 to take second. Alguersuari pops up in fifth with a 38.334.

Hamilton's first flying lap sees the McLaren driver go quickest with a 37.321, however, Vettel posts 37.255, Rosberg 36.922 and Button 36.918. On his next flying lap Vettel goes quickest in all three sectors, crossing the line at 36.053, 0.865 quicker than Button.

Approaching half-time, Trulli, Massa, Webber and Sutil are the only drivers yet to post a time. Alonso is currently sixth on 37.780.

Having gone quickest in S1 and posted a PB in S2, Hamilton backs off before heading into the pits. Kobayashi goes fifth with a 37.554 with Alonso slotting in behind on 37.555.

No sooner has Trulli posted 40.118 to go eighteenth than his teammate Kovalainen leapfrogs him with a 39.325.

Webber is on track but slows in S2 while back in the pits his crew don their rubber gloves suggesting there is a KERS issue - again. Back in the garage, the 'KERS Keep Clear' sign is placed on top of the car confirming initial suspicions. Indeed, Adrian Newey leaves the pitwall to come and check on what's happening.

21:25 on the clock and it's: Vettel, Button, Rosberg, Alonso, Hamilton, Massa, Kobayashi, Petrov, Sutil and Alguersuari.

Schumacher is the first of the big guns to switch to the soft rubber, the German immediately going second with a 36.141. Elsewhere, Rosberg, also on softs, goes quickest in the first two sectors crossing the line at 35.677 to take the top spot. Button posts 36.307 on hards.