Ahead of today's opening practice session, the air temperature is 25 degrees, while the track temperature is 23 degrees. As expected it is bright and sunny.

While most teams are saving their major upgrades for Silverstone in two weeks time, there are still quite a few upgrades being tried out this weekend, most notably Ferrari.

With convincing back to back wins in Turkey and Canada, the championships appears to be swinging away from Red Bull towards McLaren, though the Milton Keynes outfit insists that there is much more to come. That said, McLaren says that it fears Ferrari more than its Austrian rivals.

As the first cars come out for their installation laps, the timing system fails. Thankfully, it flashes up again a few moments later. Kovalainen is first out, followed by Klien, Liuzzi and a whole host of others including Alonso and Vettel.

Two teams have their test drivers in action this morning, Paul di Resta returns for Force India, replacing Adrian Sutil, while at Hispania Christian Klien stands in for Karun Chandhok.

Kovalainen, incidentally, drove through the night to Valencia in order to be here, the Finn one of several drivers who found his schedule screwed up by a strike in France.

As reported last weekend, Ferrari is running a revised rear end, the Italian team, like McLaren, Mercedes and Renault, taking a lead from Red Bull's exhaust system which blows the discharged gases through the diffuser. That said, McLaren will not introduce its version until Silverstone when Williams is also expected to go down that route.

Ten minutes into the session all have been out, Schumacher completing three laps of the Spanish track.

As di Grassi laps the circuit, Kobayashi poses for the photographers with a pitboard that reads 1 - 3, a nod to last night's victory over Denmark in the World Cup.

di Grassi posts the first time of the day, the Virgin driver crossing the line at 49.569. However, Button and Webber are both on track, and no sooner has di Grassi raised his game with a 47.938 than Button posts 43.245.

Even after three years the Valencia backdrop appears as drab as ever, a bit like Great Yarmouth but with sunshine.

Klien posts 51.583 to go third as Alguersuari, Senna and Glock head down the pitlane.

A 46.026 sees Hamilton go second as Alonso dives into the pits following a second installation lap.

The track is clearly very dusty, thanks mainly to a nearby cement factory. Nice one!

As Kobayashi splits the McLarens with a 44.476, Glock goes fourth with a 46.026. Elsewhere, Buemi runs over the wing mirror which has fallen from Senna's Hispania.

Thirty six minutes into the session it is red-flagged though initially it is unclear why. However, other than the thick (cement) dust, the cameras picks up the debris from that wing mirror which is now to be found right on the racing line.

Replay shows the mirror coming lose on Senna's car and then being blown off, hitting the side of the Brazilian's helmet and subsequently being run over by the Toro Rosso of Sebastien Buemi. Four marshals armed with big brushes head to the spot to clear the debris.

After a couple of minutes the session is all-clear again and Alonso and Massa are among the first out. Meanwhile, Buemi complains about the braking balance on his car.

Schumacher posts a 42.369 to go quickest bang on half-time, as Massa goes sixth (45.407) and Alonso fifteenth (48.524).

Schumacher, Button, Kobayashi, Buemi, Alguersuari, di Resta, Massa, Glock, de la Rosa and Hamilton.

No sooner has Massa gone second (43.218) than teammate Alonso posts 42.744 and Rosberg 42.639.

With the Red Bull drivers yet to post a time, Kubica goes fourth with a 42.885. Elsewhere, Massa, Alonso and Kobayashi take full advantage of the generous run-off at Turn 2.

Button re-takes second with a 42.247 as Hulkenberg goes fifth with a 42.707. Elsewhere, Alonso goes quickest in the first sector, losing time in the second following a slight wobble. Webber and Vettel head down the pitlane.