Ahead of today's sole free practice session the air temperature is 25 degrees C, while the track temperature is 30 degrees. It is bright and sunny.

Following yesterday's sessions it is hard to draw any serious conclusions. Nico Rosberg was quickest in the first, just ahead of the McLarens, while Fernando Alonso edged out the Red Bulls in the second.

Valencia was expected to be McLaren's track, with many claiming that the championship initiative was beginning to swing away from its Austrian rivals. However, yesterday's second session was clear evidence that Red Bull is far from finished.

While the major upgrades are expected in Silverstone, a number of teams are trying out various modifications in Spain, with some running blown rear wings/diffusers (Ferrari, Mercedes and Renault) and others F-ducts, indeed, Red Bull is expected to use its version of the F-duct for the remainder of the weekend.

Tyre options are medium (prime) and super-soft (option) however, other than the normal problems with those round bits of rubber, drivers are having to contend with cement blown in from a local factory. Nice.

After three visits the Valencia Street Circuit is as bland and uninspiring as ever, let's hope someone's getting something out of this because the sport isn't.

When the lights go green Bernie Ecclestone is standing at the very end of the pitlane, moving aside as di Grassi and Buemi get the session underway.

Timo Glock, who missed much of yesterday's second session as a result of a gearbox issue, is already in difficulties again, the German coasting around the harbour.

Seven minutes into the session everyone has been out for an installation lap.

After several (eight) minutes of inactivity, di Grassi heads down the pitlane to give the spectators something to look at. The Brazilian crosses the line at 1:43.867 as Alguersuari, Chandhok, Kovalainen, Petrov and Trulli get to work.

As Senna watches proceedings on the Kangaroo, Alguersuari raises the benchmark with a 40.623. Fernando Alonso is in the Ferrari garage talking to Marc Gene.

A 40.196 sees Hulkenberg go quickest, as all but the Ferraris and Red Bulls are on track.

His first lap an exploratory 47.140, Hamilton goes quickest in the first two sectors of his next lap, finally crossing the line at 39.338 to go quickest. Button posts 39.667 to go second but is demoted by Barrichello (39.636).

Button goes wide at Turn 10, as Kubica goes ninth and Schumacher eighth. Next time around the Pole goes quickest with a 39.123.

Force India continues to impress with Sutil going quickest with a 39.066. Teammate Liuzzi is currently thirteenth (40.599).

All eyes are on Vettel who goes quickest in the first sector and by the second split is 0.105s up on Sutil. At the line the Red Bull driver posts 38.884, a minor error at Turn 17 costing him.

As Sutil fails to improve, Alonso pops up in fourth (39.187), ahead of Hamilton, Rosberg, Button and Webber.

Setting personal bests in all three sectors, Alonso improves to second with a 38.970 as teammate Massa goes quickest in the first sector. At the line the Brazilian posts 39.374 to go seventh having lost time in the final two sectors.

Webber and Vettel are both on hot laps, the German consolidates his top spot with a 38.727 while Webber posts 38.802 to go second.

Rosberg goes third (38.911) as Alonso looks set to improve, ultimately crossing the line at 38.713. The Ferraris looking very, very good here.

With twenty-five minutes remaining, it's: Alonso, Vettel, Webber, Rosberg, Sutil, Kubica, Hamilton, Massa, Hulkenberg and Schumacher, with Button in eleventh.

A 38.981 sees Massa improve to fifth ahead of Sutil and Kubica. Liuzzi has slipped down to sixteenth.

Kubica goes second with a 38.564 having gone quickest in the final two sectors. With seventeen minutes remaining we have yet to see the option tyre make an appearance this morning.