Ahead of today's opening practice session the air temperature is 24 degrees C, while the track temperature is 30 degrees. The best way to describe the sky would be "hazy".

The big news is that as Sergio Perez suffers from a heavy cold, the Mexican will be replaced by Sauber's reserve driver Esteban Gutierrez. This is a good opportunity for Gutierrez to impress, many predicting that he will move up to a full race seat next season.

Along the pitlane, Valtteri Bottas is in Senna's Williams for this session, while Giedo van der Garde replaces Heikki Kovalainen in the Caterham.

Tyre options are hard and soft this weekend, while, as in 2011, there are two DRS zones.

Vergne and Ricciardo lead the way when the lights go green, the Toro Rosso duo followed by Gutierrez, Grosjean, Bottas, Glock and Maldonado.

An early spin for Schumacher, the track, like Korea, very green after the lack of use since last year. Within minutes all twenty-four drivers have been out, most completing a sole lap while Raikkonen completes two, as do Rosberg, Schumacher and Vettel.

As ever, flo-vis abounds, particularly on the Ferraris, while Williams is running a front wing that only arrived here yesterday. At Lotus, Grosjean gets his first taste of the coanda exhaust.

Fifteen minutes into the session Vergne looks set to post the first time of the weekend, however the Frenchman subsequently dives into the pits. In the Sauber garage, a remarkably fit looking Perez chats to Gutierrez.

There follows a long period of total inactivity, drivers out of their cars talking to teammates, engineers, team bosses, just about anyone. The fans in the stands wait patiently.

Twenty-five minutes into the session, Gutierrez is back on track. The Mexican youngster gets things underway with a 1:46.071. As he crosses the line, Maldonado, Hamilton and Button head down the pitlane - rare to see the Maccas at work so early.

No sooner has Gutierrez improves to 37.584 than Hamilton posts 37.354 and Maldonado 34.740.

As more drivers get to work the times tumble, Button posting a 32.349 only to be leapfrogged when his teammate posts 32.074. The 2009 champ responds with a 31.141.

Button consolidates his place at the top of the timesheets with a 29.684 as Bottas goes fourth and Grosjean fifth. The Frenchman subsequently splitting the McLarens with a 31.376.

Maldonado has a number of excursions, the Venezuelan struggling for grip. He pits for a nose change, his team clearly running back-to-back comparisons.

Rosberg goes second with a 30.918, his teammate one of seven drivers yet to post a time. Elsewhere, Petrov outbrakes himself in T1.

Massa goes tenth with a 30.032 before improving to second with a 30.009, just 0.325s shy of Button. Hulkenberg goes fourth (30.603) and Schumacher fifth (30.836).

As Rosberg improves with a 29.811 Alonso goes eighth (31.011), leaving the Red Bull duo and Glock as the only drivers still to post a time. That said, all three are now on track.

On their first flying laps, Webber goes sixth (30.252) and Vettel eighteenth (32.502). Glock can only manage 34.957. Webber subsequently goes quickest with a 28.963 as Schumachers takes second (29.598).

As Vettel goes second (29.251), with 34:20 remaining, Hamilton is still seventeenth having only completed 8 laps. By comparison, Maldonado has completed 16 laps.

Grosjean runs wide at T9 as Alonso goes third (29.551) and Bottas carries out front wing comparison runs.

With half-an-hour remaining, it's: Webber, Alonso, Button, Vettel, Schumacher, Rosberg, Massa, Ricciardo, Hulkenberg and Maldonado. Webber and Alonso both on exactly the same time (28.963).

Going quickest in the two final sectors, Webber ups the ante with a 28.229. Moments later, Rosberg goes quickest in S1 but loses ground in the two final sectors.

Vettel re-establishes Red Bull's supremacy by posting a 28.532, thereby going second to his Australian teammate. The German subsequently complains of traffic.