We're still scratching our heads, says Schuey

During the race, Schumacher was overtaken by the Williams of Juan Pablo Montoya and then again by eventual winner David Coulthard. The German was forced to settle for second place behind the Scot, but immediately after the race, Ferrari technical director Ross Brawn leapt to his defence by saying there must have been a problem with the triple world champion's F2001.

However, despite extensive tests at its Maranello base, the team has yet to get to the bottom of the problem and will head to this weekend's San Marino GP still unsure of what slowed Schumacher down.

"We have not found exactly what went wrong," said Schumacher. "The problem is that we cannot simulate the conditions in Brazil at Fiorano. The circumstances there were rather extreme. It was obvious there was something wrong. We were nowhere in conditions in which we usually shine - rain."

Although the Italian team has yet to isolate the problem, Schumacher feels sure he will not be hampered at Imola this weekend.

"We went into the race with a full dry set-up, as we did in Malaysia," he said. "But we were far from being as competitive as in Sepang, so it must be something track-specific. I presume we will be more competitive at Imola."