Sauber left scratching heads

Felipe Massa and Nick Heidfeld were 17th and 19th respectively at the end of the second session, with only Mark Webber's Minardi slower.

Sauber said: "I don't yet understand the problem we had with both cars today. Fortunately, on a high-speed circuit of this nature, even small changes can have a significant effect, but it is clear that we have a lot of work to do in order to indentify what set-up changes we need to make to improve the situation tomorrow."

Neither driver felt comfortable driving the C21. Massa said: "I had massive understeer in the low and medium-speed corners, and the car was extremely nervous in the high-speed sections. It wasn't nervous under braking, however, but I had a problem with the brake balance and flat-spotted two sets of tyres, so I set my best time on old tyres."

Heidfeld also suffered from handling difficulties. "The car was very nervous today, but at least it's reliable," he said. "I had some traffic on my best lap but I don't think it made a great deal of difference."