At that time Barrichello was setting the pace, with his lap of one minute 15.487 seconds the only serious effort from a top driver.

The slippery track meant his time could not be beaten, with only test drivers and backmarkers bothering to try their hand in wet conditions.

Juan Pablo Montoya was one of the few front-runners to go out on the wet track and he quickly came a cropper.

The Colombian lost control of his Williams under braking at the midpoint of the one-hour session and bounced at high speed through a gravel trap.

Montoya was fortunate not to roll over after flying through the air and digging into the wet gravel. His car eventually thudded to a halt with three of its four corners showing considerable damage.

The wet track meant lap times were up by around 15 seconds and the classification at the end offered little clue as to how the weekend will play out.

The standings were dictated more by luck than speed, with Michael Schumacher a quarter of a second behind Barrichello and a host of surprise names following him.

Marc Gene, who is replacing the injured Ralf Schumacher for Williams at Magny Cours, was third quickest, almost four seconds down.

The Jordan trio of tester Timo Glock, Giorgio Pantano and Nick Heidfeld were fourth, fifth and sixth respectively after benefiting from their decision to hit the track early.

The rest of the grid never got a fast lap in before the showers started.

Jenson Button was back in 11th for BAR over 12 seconds down after just one quick lap while David Coulthard never even completed a full lap in his McLaren.