Ahead of today's second practice session the air temperature is 22 degrees C, while the track temperature is 44 degrees. It remains bright and sunny.

The lack of grip caught out a number of drivers this morning, not least Sebastian Vettel who added his name to the growing list of world champions who have hit the notorious champions' wall on the pit straight.

Nico Rosberg was quickest, ahead of Fernando Alonso and Michael Schumacher with the McLaren duo hot on their heels. The Red Bull duo, who face their biggest challenge of the season this weekend, could do no better than twelfth and sixteenth.

The big news is that following this morning's session, Sauber has opted to replace Sergio Perez with (McLaren test and reserve driver) Pedro de la Rosa. The Spaniard will replace the Mexican, who crashed heavily in Monaco two weeks ago, for the remainder of the weekend. Apparently Perez felt unwell during this morning's session.

The lights go green and Alguersuari is first out followed, shortly after, by Kovalainen, di Resta, Karthikeyan, Kobayashi, d'Ambrosio and Petrov.

Alguersuari posts the first time of the afternoon, the Spaniard crossing the line at 21.955. Moments later di Resta posts a 20.038.

On his first flying lap, Massa, who goes quickest in S3, posts a 21.633 to go fifth. Meanwhile, di Resta improves with a 19.093.

Heidfeld goes quickest in the first two sectors and again in the third, the Renault driver crossing the line at 17.499 to go quickest. Massa goes second and Petrov third.

As Barrichello posts 18.654 to go fourth, Heidfeld raises the benchmark with a 17.499.

On his first flying lap, Webber goes fourth (18.051) as teammate Vettel begins his first flying lap. Hamilton, Button and de la Rosa have yet to make an appearance.

As Massa is told to try lifting and cruising in the hairpin, in an attempt to cool his brakes, Webber improves to second with a 17.243. Teammate Vettel goes eighth with a 19.042 before improving with a 16.262 to take the top spot. None the worse following his crash this morning, the German posts a 15.739 to raise the bar ever higher.

Hamilton goes third, ahead of Alonso, Heidfeld, Massa, Petrov and Maldonado.

Replay shows Massa getting his rear end very, very close to the champions' wall. The Brazilian was world champion for around twenty seconds at the end of 2008.

Even though the track is becoming a little less 'green' with every lap, drivers continue to struggle, whether it's drifting just a little too close to a wall, locking up or missing the chicanes.

After thirty minutes de la Rosa has yet to make an appearance.

Sutil, who, like Buemi, didn't take part this morning, goes fifth with a 16.905. Massa continues to tempt fate in terms of the champions' wall.

As Vettel gets into all sorts of trouble at Turn 8 (the other chicane), Alguersuari is the first driver to switch to the option (supersofts).

At the entrance to the pitlane a marshal is waving a slippery surface flag.

Having gone quickest in S1 and posted a PB is S2, Hamilton misses the final chicane. Consequently the McLaren driver remains fourth on 15.977.

Alonso goes quickest with a 15.205, the Ferraris looking good here this weekend. Teammate Massa is currently third (15.601) sandwiching Vettel.

Trulli, currently twentieth (21.005), switches to options, immediately improving to seventeenth (19.051).

Sutil hits the barriers after Turn 7, ripping off the front-left. The German, who was on options, had improved to tenth (16.905), and looked likely to improve again having posted a PB in S1.

At Renault, Petrov and Heidfeld are running different rear wings, the Russian is currently seventh and his teammate eighth.

Sauber's weekend goes from bad to worse as Kobayashi clouts the barriers just after Turn 4. The Japanese driver is fine but the front of the car is badly damaged. As the session is red flagged we have yet to see de la Rosa make an appearance.