Ahead of today's second session, the air temperature is 17 degrees C, while the track temperature is 29 degrees.

While McLaren and Mercedes dominated the opening session, the big news was Fernando Alonso's engine problem and the spectacular incident that wrecked the front of Sebastien Buemi's Toro Rosso. While Ferrari is keeping its cards close to its chest, only revealing that the unit was the same one used in the opening sessions in Bahrain, Toro Rosso has revealed that its driver's crash was due to the failure of the front right upright.

While the exact reason for the failure of the upright - which was a new design - is not yet clear, we do now know that only the right hand component failed, the left hand side failing (almost simultaneously) due to the excessive load put on it when its sister unit failed.

The lights go green and Karun Chandhok is first out, followed by Fernando Alonso, who failed to post a time this morning. The Spaniard is running Ferrari's own version of the controversial F-duct today, though no doubt that's the last thing on his mind.

Chandhok posts the first time of the afternoon (43.809) but this is soon beaten by Kobayashi who crosses the line at 39.565.

Toro Rosso get a much needed boost when Alguersuari posts 38.559 to go quickest.

Nine minutes into the session, Button goes quickest in the first sector, as Alguersuari consolidates the top spot with a 38.091. As Button goes quickest in the second sector, Webber and Hamilton are also on hot laps.

Button posts 36.988 to go quickest, but a 36.639 from his teammate sees Hamilton go quickest. Webber dives into the pits.

Next time around, Button improves with a 36.206, to go quickest, however, Hamilton crosses the line at 36.033. That said, the 2008 world champion is losing time to his teammate in the final sector.

Behind the McLarens, it's Kubica, Sutil, Petrov, Barrichello, Kobayashi and Hulkenberg.

As Schumacher posts 37.514 to go fifth, Webber, Rosberg and Buemi are the only drivers yet to post a time. Alguersuari complains of a lack of grip at the rear of his car, ironic considering the failure that befell his teammate.

Rosberg posts 39.464 to go fourteenth. Next time around he goes quickest in the second sector finally crossing the line at 36.019 to go quickest overall by 0.014s.

The Ferraris are playing it cautious, Alonso fifteenth (39.348) and his teammate sixteenth, as Rosberg raises the benchmark with a 35.674. Webber posts 36.605 to go sixth, forcing Schumacher down to seventh.

Alguersuari, one of the first to switch to the option (soft) tyre improves to fourth with a 36.377. Most of his rivals appear to be on longer runs running the prime (hard) tyres at this stage.

The understeer on his car through Turn 14 for Senna is all too much, he lifts his hand in obvious frustration.

As Hulkenberg runs wide, taking to the green run-off, Schumacher, like many others, is suffering chronic understeer.

Liuzzi and Kobayashi appear to think its Sunday afternoon, the due virtually wheel to wheel on the back straight. All a bit pointless really, especially when the Sauber driver dives into the pits.

Petrov (soft) posts personal bests in the first two sectors, however, he abandons the lap on the back straight.

At half-time, it's: Rosberg, Hamilton, Button, Sutil, Alguersuari, Webber, Schumacher, Kubica, Petrov and de la Rosa. All the usual suspects - Lotus, Virgin and Hispania - at the bottom of the timesheets while Buemi has yet to appear.

Hamilton, now on softs, goes quickest in the first two sectors, and again in the third, crossing the line at 35.217 to go quickest. Having completed a very slow out lap, teammate Button begins a flying lap, also on the option tyres. However, having lost a heap of time behind di Grassi, the Englishman has to abort the lap, making the Brazilian fully aware how he feels.

On his next lap, Button can only go quickest in the final sector, crossing the line at 35.593, 0.376s down on his teammate.

Rosberg (option) posts a personal best in the first sector, and again in the second. At the line the German posts 35.465, thereby splitting the two McLarens.