Michael Schumacher led a Mercedes GP 1-2 in the opening practice session at the Belgian Grand Prix, but the timesheet does not tell the full story as a heavy rain shower and ensuing tricky conditions made it impossible for anyone to get near to their times.
The Ardennes had already shown its fickle nature by the time the F1 boys ventured out, having dawned bright and sunny, but already suffered a couple of showers before and during initial GP3 Series practice. The track was dry for the start of the F1 session, but only a handful of drivers had completed a lap by the time the heavens opened, with Schumacher and Nico Rosberg the only ones to set a time.
The intensity of the shower drove everyone to seek shelter for almost five minutes, and rain continued to fall, albeit more lightly, for a lengthy period thereafter, limiting running and the benefits that could be derived from it. Sebastian Vettel and Lewis Hamilton were among the first to return to the track, but both suffered moments that made them think otherwise about pushing on.
As the track began to dry, however, the Spa-Francorchamps crowd were gradually treated to more and more action, with McLaren's Jenson Button again showing his ability in mixed conditions by moving to the head of the 'wet' times. Two accidents - to Renault new boy Bruno Senna and Force India's Paul di Resta - eventually prompted the stewards to throw a temporary red flag, but Button was again 'on it', lowing his previous best by seven seconds before the chequered flag came out.
The Briton subsequently moved into third spot on the timesheets, but the gulf between wet and dry times was underlined by the eight-second gap separating him from the two Mercedes drivers, Schumacher having clocked 1min 54.355secs to Button's 2min 02.740secs.
There were precious few incidents despite the conditions, and all 24 drivers completed at least seven laps apiece, with some, including Rosberg, Adrian Sutil, Jaime Alguersuari and Kamui Kobayashi achieving nearly double that. Vettel and Hamilton eventually completed the top five, with Sutil, Felipe Massa, Rubens Barrichello, Alguersuari and Kobayashi rounding out the top ten.
Senna and di Resta were left in 23rd and 20th positions respectively after their turn nine incidents, unable to make the best of the drying conditions, while rookie Daniel Ricciardo brought up the rear in the second of the HRTs.
Team Lotus' Jarno Trulli, by contrast, finished higher than expected, in 13th, three places ahead of Red Bull's Mark Webber, while reserve team-mate Karun Chandok was 21st on his latest outing in the green-and-gold machine.