Ahead of today's opening free practice session, the air temperature is 15 degrees C, while the track temperature is 15 degrees. It is overcast, to put it mildly. Although it is not raining at present, the track is still damp following lots of overnight rain,

The lights go green and Sutil leads the way, followed by Heidfeld, Vettel, Piquet, Bourdais, Kubica et al.

No sooner has the session started than it starts to rain, albeit lightly, on the far side of the circuit. However, just moments after the first batch of drivers have completed their installation lap, the rain promptly stops.

Seven minutes into the session, Glock heads down the pitlane, leaving the Ferrari duo as the only drivers yet to appear.

As Fernando Alonso paces back and fourth in the Renault garage looking quite agitated, race control reports that there will be no further rain during the session. Time will tell.

Thirteen minutes into the session, Raikkonen heads down the pitlane. The Finn has won the last three Grands Prix here, he needs another good result this weekend. As the Finn begins his first flying lap, teammate Felipe Massa leaves the Ferrari garage.

Rather than post a time, the World Champion dives into the pits at the end of his flying lap, watched by Ferrari test driver Luca Badoer. Sutil, Vettel, Bourdais and Webber are all on track as Massa posts the first time of the day, 1:50.329.

Sutil goes second but is immediately leapfrogged by Vettel (50.616), as Massa improves with a 48.945.

As Massa improves with a 48.209, Hamilton goes second (49.784), only to be nudged down to third by Vettel (49.663). However, moments later, Alonso goes second with a 49.251.

As Raikkonen heads down the pitlane, meaning that all twenty cars are on track, Hamilton re-takes second with a 48.787.

A 46.768 sees Alonso go second, however, as Raikkonen returns to the pits, having failed to post a time, Hamilton posts 48.266 to re-take second spot.

Piquet gets it all wrong at the chicane that leads on to the pit straight. However, next time around the Brazilian goes tenth with a 50.434. Elsewhere, Kovalainen goes sixth, behind the two Toro Rossos.

As Trulli goes quickest in the second sector, Raikkonen is back on track. The Italian subsequently posts 49.898 to go seventh, as Piquet improves to sixth.

Kovalainen makes it a McLaren 1-3 with a 48.734, as Raikkonen begins another flying lap. However, having got all crossed up at La Source it's a poor first sector time for the Finn.

While the first six are covered by 0.986, the Red Bulls, Hondas and Williams all remain over 2s off the pace.

Raikkonen goes third with a 48.452, thereby splitting the McLarens. Next time around, the World Champion takes the top spot with 48.075.

"It's totally unpredictable because of the tyres," laments Kubica, "I cannot steer, I brake, I cannot do anything. I wasn't pushing on the brakes because I was scared."

Vettel takes a drive across the Belgian countryside, as Massa re-takes the top spot with a 47.813.

The tyre options are hard and medium this weekend, and Heidfeld is one of the first to try the softer (medium) compound. The German improves to eleventh with a 50.038. We will refer to the compounds as hard (hard) and soft (medium).

At 'half-time', it's: Massa, Raikkonen, Hamilton, Kovalainen, Alonso, Vettel, Bourdais, Piquet, Glock and Trulli.

As Coulthard seeks to improve on twentieth, 3.9s off the pace, he's warned that the "rain is coming in earlier than expected". There has been talk of the Scot being dropped before the end of the season, and the news that Sebastian Vettel is to test the Red Bull at Jerez will not help the situation. That said, DC improves to eleventh with a 50.004.

Rosberg pits and has a different nose fitted, Williams clearly using the session to run a 'back-to-back test.

With just over thirty minutes remaining, Hamilton and Kovalainen are back on track, as is Raikkonen. In the BMW garage, Christian Klien looks desperate to get into Kubica's car, the Pole still clearly uncomfortable with the F1.08 on this track.

The final chicane before the pit straight is catching out a lot of drivers, the latest being Barrichello, who is trying to improve on nineteenth.