Ahead of today's all-important qualifying session, the air temperature is 25 degrees C, while the track temperature is 43 degrees. It remains bright and sunny.

While this weekend was expected to favour McLaren, it would appear that Red Bull still has the edge.

With the tight confines of the 24-corner street track expected to limit the Austrian cars, which seem more at home on flowing higher-speed tracks, the Milton Keynes outfit has served notice that it can raise its game when needed. Indeed, as Red Bull fights back it is McLaren that appears to struggle, with Ferrari, Renault and even Force India giving the Woking outfit a good run for its money this weekend.

McLaren, though saving its upgrades for Silverstone, was expected to shine here, and its performance in yesterday's opening session bore this out. However, ever since the team has appeared to struggle, to the extent of Button having a gurney flap fitted during this morning's session.

Red Bull is running its version of the F-duct this weekend, while Ferrari, Mercedes and Renault are running their versions of the so-called blown diffuser, a revised layout at the rear of the car which forces exhaust gases through a gap in the diffuser, thereby aiding aerodynamic efficiency. While this was pioneered by Red Bull, it is ironic that the Austrian team is now running the F-duct system devised by McLaren.

The tyres available this weekend are medium (prime) and super-soft (option), with Ferrari, in particular, appearing to struggle with the softer option this morning. Though these are the two options used in Canada we do not expect tyres to as significant here as they were in Montreal.

Despite previous expectations, it is expected that Red Bull will now continue where it left off in Turkey, certainly in terms of qualifying, however, it remains to be seen whether the Austrian team can return to its winning ways, especially with reliability still an issue.

While McLaren now looks to have to regard this weekend as damage limitation, it will be interesting to see how Ferrari, Renault and Force India perform. Mercedes, despite that improvement a couple of races back, continues to disappoint.

One small factor worth noting is that the organizers of the GP2 event have shortened the length of today's Feature Race due to issues with fuel consumption. Could this possibly be a problem in tomorrow's Grand Prix?

The lights go green and first out is Trulli, followed by Glock, di Grassi and Kovalainen.

The Italian posts the first time of the afternoon, his Lotus breaking the timing beam at 1:44.542. Moments later Glock posts 43.683 and Kovalainen 42.308.

As Hamilton, Button and Alonso leave the pits, Hulkenberg posts 39.758 to go quickest.

Alonso goes second to Hulkenberg with a 40.0285 but is demoted when Button posts 39.467 to go quickest.

A 39.288 sees Massa go quickest, as Liuzzi goes fourth, ahead of Alguersuari, Buemi, Kobayashi and Alonso. Most drivers on an initial four-lap run.