Ahead of today's second free practice session, the air temperature is 28 degrees C while the track temperature is 38 degrees. It is still fairly overcast.

Mark Webber led the way this morning, ahead of Petrov, Alonso, Hamilton, Heidfeld, Massa, Button and Sutil. Vettel was well down the timesheets in sixteenth, but it is understood that this is because of the programme his team was running. In fact, the German completed 21 laps which was well in line with most of his rivals.

We didn't see the soft Pirellis this morning but that will change over the next ninety minutes.

Although a number of drivers ran wide on the 'green' dusty surface this morning only Nico Hulkenberg came to grief, the German clouting the wall with Paul di Resta's Force India.

A number of teams are running new components this weekend, even Hispania, though the Ferrari is running in Montreal spec. McLaren has a new rear wing and front wing, Lewis Hamilton doing back-to-back comparison runs in the opening session. Williams ran a new exhaust, new floor and new rear wings, however, the Grove outfit reverts to the old exhaust this afternoon.

Jerome d'Ambrosio gets the session underway, the Virgin driver having the track to himself for around a minute before Petrov, Kovalainen, Perez and Karthikeyan head down the pitlane.

D'Ambrosio posts a 47.730 but this is soon beaten by Kovalainen (47.234) and Perez (44.432).

As more and more drivers pour on to the track the times tumble, six minutes in Massa goes quickest with a 42.048. Moments later, continuing to demonstrate Renault's good pace here, Heidfeld goes quickest with a 41.678.

Having posted a 49.722 on his first lap, Alonso goes quickest in all three sectors crossing the line at 40.492 to go quickest.

Vettel is on track and giving gone third (40.946) on his first flying lap, fails to improve on the second. However, next time around he goes quickest in the first sector, the second and the third, crossing the line at 40.062 to take the top spot.

As Alonso runs wide, one of several drivers to do so as grip remains a problem, Webber posts 40.341 to make it a Red Bull 1-2. Fifteen minutes into the session, all but Rosberg, Alguersuari and di Resta have posted times - Force India still working on the Scot's car after this morning's accident.

Vettel improves with a 39.790, the German now in full Valencia mode. Teammate Webber runs wide as Alonso goes quickest in the first sector. The Spaniard loses a little ground in the second sector but posts a PB in S3, thereby moving up to second with a 39.960.

Webber re-takes second with a 39.792 as one of the Virgins lifts some of the Astroturf after running wide across the kerbs.

Maldonado is one of the first drivers to make the switch to the soft (option) rubber, the Venezuelan responds by going fourth with a 40.301.

Rosberg, Liuzzi and Kobayashi all make full use of the run off at Turn 1, indeed, the Japanese driver runs wide at three different corners in one lap.

Alonso (prime) goes quickest in S2 but a poor final sector means he fails to improve. Elsewhere, with an eye on Sunday's race, Rosberg is on a long run (13 laps).

Button complains that he's really struggling for rear grip and suffering massive oversteer at high speed.

Karthikeyan, who slows for the pit entry, gets in the way of Alonso, the Spaniard using both hands to vent his frustration.

Approaching half-time, di Resta and Alguersuari have yet to make an appearance, the Scot, in particular, looks thoroughly hacked off as he waits on the pit wall.

At half-time, it's: Vettel, Webber, Alonso, Massa, Maldonado, Heidfeld, Petrov, Hamilton, Barrichello and Sutil.

Alonso is on a hot lap on primes however, it's hard to differentiate between the white (prime) and yellow (option). The Spaniard, having gone quickest in S1, improves his time but remains third overall.

Heidfeld (option) goes quickest overall (39.040) having gone quickest in the final two sectors.

Rosberg (options) goes quickest in S1, maintaining the pace in S2. At the line it's 39.012 the German thereby going quickest by 0.028s.