Bumpy track to blame says Sauber

Mika Salo suffered a rear wing failure in free practice, while team-mate Pedro Diniz was hit by a similar problem during qualifying.

The team chose to withdraw both cars from Sunday's race on safety grounds.

Further investigations by Sauber showed that as a result of the Interlagos bumps, both cars were exposed to severe impact loads.

A statement issued by the Swiss outfit said: "The construction of the wings, and the combination of materials used, is different to last year's successful C18 design, but we are satisfied that the surface characteristics were directly responsible for the failures.

"Sauber has always placed the highest priority on safety, and in Brazil this meant not just the safety of Mika and Pedro, but that of their fellow drivers.

"We simply could not risk running the cars without knowing precisely why the wings failed."