Hamilton quickest in Spa practice

Thankfully, after the first session was disrupted by rain that fell steadily for an hour, the black clouds lifted for a dry run in the afternoon.

With virtually every driver running for around 30 laps, the lead changed hands several times during the 90 minutes before Hamilton emerged in front.

After his victory in Hungary and second on Sunday in Valencia at the European Grand Prix, the 24-year-old is poised for a podium finish for a third successive race.

Hamilton topped the timesheets in his McLaren with a lap of one minute 47.201 seconds around the renowned 4.5-mile Spa circuit.

The unpredictability of the track resulted in the top-six places being filled by drivers from six different teams.

Toyota's Timo Glock was a surprising second quickest given his team's woes of late, just 0.016secs behind Hamilton, with Kimi Raikkonen third in his Ferrari, a mere 0.084secs adrift.

The Finn, though, did finish the session by being helped off the track by marshals after running onto the grass at the right-hand Fagnes turn.

Red Bull's Mark Webber, Renault rookie Romain Grosjean and Force India's Giancarlo Fisichella completed the top six, followed by the second Toyota of Jarno Trulli.

Sebastian Vettel, who sat out the first session to preserve engines after blowing two Renault powerplants in Valencia, finished 10th, completing 25 laps.