Williams says failures only minor

Pastor Maldonado only managed 52 laps across Thursday and Friday, as a rear wing actuator issue, a KERS problem and then a crash curtailed the rookie's mileage.

Rubens Barrichello cover 99 laps yesterday and 103 today - setting the fastest lap of the week in the process - but did not have a trouble-free run, stopping on track with a hydraulic leak today after having a KERS glitch on Saturday.

Michael said all the faults involved were minor.

"We did suffer from a hydraulic leak during the middle of the day but overall, it's encouraging that we've had no major fundamental failures on the car - especially considering how tight the package is," he said.

"All of the faults that have been causing our downtime in the recent days are small things that systems will quickly put right."

He was very pleased with today's mileage, when the team ran without KERS.

"Nothing was going to stop us from doing over 100 laps today!" Michael joked.

"After limited running up to now, we concentrated on set-up and long runs. Rubens was trying various things to learn about the Pirelli tyres - some worked, some didn't. Now we've also gathered some data on the Pirelli wet tyre after a small shower at the end of the session.

"At the next test we will also have KERS back on the car as we ran without it today."

Barrichello agreed that today had been a breakthrough.

"This morning was also the first time we could run a few new sets of tyres and get some momentum," he said. "The car performed as it should do so I am happy with that.

"The day went with minor problems, but we have some good direction and it is great to get some more mileage on the car."