Ahead of today's opening free practice session, the air temperature is 25 degrees C, while the track temperature is 35 degrees. It is bright and sunny.

Paul di Resta is in action for Force India this morning, The Silverstone-based outfit opting to give the Scot his F1 GP weekend debut. Adrian Sutil will sit out the session while Tonio Liuzzi drives the second car.

The lights go green and Trulli leads the way, followed by Liuzzi, Buemi, Kovalainen and di Resta.

Having missed all three practice sessions in Bahrain, Karun Chandhok sits patiently in the HRT as teammate Bruno Senna heads down the pitlane.

Webber is the first of the big guns to take to the track, the Red Bull driver being tipped as a potential winner of his home race this weekend having finally opened his win account last year at the Nurburgring.

Five minutes into the session all but Schumacher have been out for an installation lap, yes, even Chandhok.

Following McLaren's introduction of a device - now known as the F-duct in Bahrain, Sauber is running a prototype version with Red Bull and Mercedes also looking at the possibility of running a similar system in the not too distant future.

The F-duct alters the air flow to the rear wing, stalling the air to reduce drag and thereby increase top speed. The McLaren drivers are believed to operate the system inside the cockpit by using their left knee.

Meanwhile, since Bahrain the FIA has ordered a couple of teams, including Red Bull and McLaren, to reduce the size of the hole in their diffusers ostensibly meant to accommodate the starter motor, but in reality a cunning means of creating more downforce.

Once Schumacher has completed his installation lap there is the usual period of total inactivity bar drivers chatting and joking with their crew.

Twenty minutes into the session, Senna breaks the deadlock, the Brazilian's HRT throwing up a shower of sparks as the skidplate meets the bumps of Albert Park. He crosses the line at 1:39.329, going 0.845s quicker in the first sector of his next lap. At the second split he's 1.62 to the good, finally crossing the line at 37.989.

As Senna returns to the pits, di Grassi heads out of the Virgin garage, with a little assistance from his crew, the pitlane worryingly narrow at his end. Moments later, the Brazilian is joined by Chandhok.

Di Grassi's first lap sees the Virgin driver post 40.581 while Chandhok - on his first ever F1 practice lap goes quickest with a 37.978. Hamilton, Kovalainen, di Resta and Petrov are now on track.

A 36.810 sees Kovalainen go quickest, however, this is soon beaten by his former teammate, Hamilton posting a 30.076, despite losing time behind Petrov in the final sector. di Resta goes second with a 33.765, as Petrov posts 34.389 to go third.

Hulkenberg, who was disappointing in Bahrain, is now on track, as Kobayashi and de la Rosa make it a Sauber 2-3. Meanwhile, Hamilton raises the benchmark with a 28.680.

Kobayashi goes off at Turn 12, after losing his front wing when colliding with a marker cone. Elsewhere, Schumacher goes second with a 30.734.

The session is red flagged as the debris from Kobayashi's car is cleared from the track.

After 43 minutes, it's: Hamilton, Schumacher, Kobayashi, Petrov, de la Rosa, di Resta, Rosberg, Hulkenberg, Chandhok and Kovalainen.

When the session resumes Rosberg, Webber, Vettel, Kubica, Button and Barrichello are the first out.

Webber's first lap sees the Australian go fifth (32.331), only to be demoted by his teammate who crosses the line at 32.188. Moments later, both are demoted when Kubica goes second with a 29.886.

Rosberg goes second with a 29.278 as Vettel and Webber go third and fourth, only to be demoted when Button goes third with a 29.541.

Rosberg improves again, this time going quickest with a 28.357, however, moments later Button goes quickest in all three sectors finally crossing the line at 27.798.

With thirty-seven minutes remaining, the action is really hotting up, Rosberg goes quickest with a 27.659 as Hamilton improves with a 27.793.

Alonso is the first of the Ferrari duo to post a time, the Spaniard crossing the line at 29.603. Next time around, despite losing time behind Alguersuari, he improves with a 29.173.