Ahead of today's first free practice session, the air temperature is 24 degrees C, while the track temperature is 30 degrees C. It is bright and sunny and warm, wholly different from the Nurburgring two weeks ago.

Today marks the first driver change of the 2009 season, with Jaime Alguersuari taking Sebastien Bourdais' seat at Toro Rosso, thereby becoming the youngest driver in F1 history.

Tyre options this weekend are soft and super-soft, while, once again, only McLaren and Ferrari will be running KERS.

After two disappointing races, Brawn will be looking for a return to form this weekend, the circuit, with its numerous slow corners, and the warmer weather, should certainly help. The Brackley team will also be aided by a number of new components including a revised front suspension, revised diffusers and some new bodywork.

The lights go green and Vettel is first out, followed by Buemi, Kubica and new boy Alguersuari. The Spanish youngster is cautious, perhaps overly so.

"I have a good feeling from the car," the youngster tells his crew on his return to the pits, "everything worked OK, even the drinks button."

At long last, the Toro Rosso is running an aero package similar to that on the Red Bull, consequently we should see a step forward in the latter stages of the season.

While the majority of drivers complete one installation lap, the BMW duo completes two. Eight minutes into the session, all but Glock have made an appearance.

Alguersuari is back on track the youngster enjoying the benefit of having the track to himself. He remains cautious, finally crossing the line at 1:34.716. Next time around the reigning British F3 champion raises the benchmark with a 31.457.

As Glock finally makes an appearance, eighteen minutes into the session, Alguersuari posts 27.953 as the Spaniard continues to gain confidence.

A 26.727 sees Toro Rosso teammate Buemi go quickest as Hamilton, Button, Barrichello and a couple of others come out for a second installation lap.

As the rest of the drivers watch proceedings form their garages or from the pit-wall, Alguersuari goes quickest with a 25.585. However, moments later, Buemi posts a 25.034.

All this is watched by Nelson Piquet at the back of the Renault garage, the Brazilian admitting yesterday that his position is under threat. Indeed, he believes he could be dropped before the end of the season.

The BMW is sporting a revised nose and wing, not entirely dissimilar to the tusks seen on the Williams-BMW a couple of years back.

Thirty-one minutes into the session, Trulli is the third driver to post a time, the Toyota driver crossing the line at 27.488. Moments later Glock posts 28.426.

A 24.983 sees Trulli go quickest as Raikkonen leaves the pits. After this weekend's race - thought by many to be one his last before he retires from F1 - the Finn is heading home to contest the 1000 Lakes Rally.

As Raikkonen improves from fifth to fourth with a 25.273, Massa posts a 25.105 to demote his Ferrari teammate.

Alonso posts 24.861 to go second as Rosberg goes seventh behind Raikkonen and Massa.

Trulli consolidates the top spot with 24.057, as Alonso also improves and Massa goes third. Next time around the Brazilian improves with a 23.735 to take the top spot. Alguersuari remains ninth (of eleven) just 1.658s off the pace.

At half-time, it's: Massa, Rosberg, Alonso, Trulli, Kubica, Vettel, Buemi, Glock, Nakajima and Raikkonen. No times yet from Heidfeld, Button or Hamilton, though all three are on track.

Vettel goes quickest with a 23.713 only to be almost instantly demoted by Rosberg who posts 3.268. Hamilton, on his first timed lap, goes nineteenth with a 28.747.

Kubica takes the top spot with a 23.219 as teammate Heidfeld improves to sixteenth with a 24.792.

A 22.615 sees Nurburgring winner Mark Webber go quickest as Hamilton goes second ahead of Kubica and Rosberg.