Colombian Juan Pablo Montoya made a nightmare start to his French Grand Prix weekend when he crashed his Williams in Friday's rain-hit first practice.

Montoya, hoping for a strong result at Magny-Cours after suffering two disqualifications in a row, skidded at turn six before he had completed a timed lap on a track made slippery by a sudden downpour.

The Colombian was unhurt but the car, which bounced and flew across the gravel before slamming into a tyre wall, was shattered by the impact and needed extensive repairs before the afternoon session.

"A big compliment to the mechanics," said BMW motorsport director Mario Theissen.

"They fixed the car in two and a half hours and did a great job. He can drive with his normal car and no engine change was necessary."

The team said Montoya, disqualified in Canada for using oversized brake ducts and in the United States for an infringement involving the spare car, appeared to have been going simply too fast.

Williams won in France last year with Ralf Schumacher leading Montoya in a one-two finish in a race that triggered the Colombian's decision to join McLaren for 2005.

Ralf has been ruled out for up to three months after crashing heavily and suffering spinal fractures at last months' U.S. Grand Prix.

Spaniard Marc Gene is standing in and finished with the third best time in the morning session and 14th best in the afternoon.

BARRICHELLO FASTEST

The showers, interspersed with sunshine and blustery conditions, continued in the afternoon and both sessions were declared wet -- a decision that gave the teams until noon on Saturday to finalise their choice of tyres.

The Ferrari drivers beat the showers, Brazilian Rubens Barrichello clocking the day's fastest time of one minute 15.487 early in the first session before the clouds broke.

Six-times world champion Michael Schumacher was second quickest, 0.226 slower than Barrichello, but the times meant little.

Brazilian Cristiano da Matta was fastest in the afternoon for Toyota, popping in a quick lap of 1:15.518 as the session ended on a drying track.

McLaren's heavily revised MP4-19B car made a low-key debut at a race weekend, Briton David Coulthard seventh fastest in the afternoon after neither he nor Finland's Kimi Raikkonen had set a time in the morning.

The Mercedes-powered team, a distant fifth in the championship, are looking to the car to revive their fortunes.