Ralf: 'I am not happy'

The Malaysian Grand Prix winner was only 10th on the first day of practice for this weekend's race, while his team-mate Juan Pablo Montoya was only one place further up the order.

Schumacher suffered a nummber of spins on the wet track, during two sessions which proved that the Michelin tyres are inferior to Bridgestone's when it rains.

"I am not happy, as one can easily understand from my lap times," said Schumacher. "Unfortunately the continuous rain didn't allow us any true improvement. There is still a lot of work to do ahead of us."

Earlier this week, the team's chief operations engineer Sam Michael told AUTOSPORT magazine that the San Marino GP was "vital" for Williams to keep up its world championship challenge to Ferrari. If the drivers continue to struggle over the weekend, they could both lose ground to Michael Schumacher and Rubens Barrichello, who were first and second quickest today.

After practice, Michael said: "We tried different wet tyres that were available. We spent time on set-up during the day trying to get the best out of the tyres and this has given us a lot of data to go through tonight. We are not there yet on the wet set-up and we still have a lot of work to do on both cars with ourselves and our partners."