Brawn drivers admit to grip concerns

Barrichello could only manage the eighth fastest time in the second session, four places higher than world championship leader Button, while neither made it into the top ten in the morning session.

"It's been a slightly different Friday today from our recent experiences," said the Brazilian. "We don't look that competitive at the moment however it is still early in the weekend and depends on the programmes and fuel levels that our competitors are running.

"There is a lot of work for us to achieve, particularly in the first sector where we seem to be suffering the most, but we believe that we understand the issues.

"We know that we can work with this car to improve its performance quickly and that puts us in a strong position to make the changes needed ahead of qualifying."

Button, who currently enjoys a 15-point lead over team-mate Barrichello, added that while Friday had been tough he was confident the team would improve through the weekend.

"We've had a tough first day of practice trying to find a good balance with the car," he said. "We tried many different set-up options over the course of the two sessions but unfortunately could not get the car to where I want it to be and struggled with a lack of grip. However we now have a great deal of information to review after trying a few evaluations and believe that we have some understanding of what is causing the problems.

"We need to have a good look at everything tonight and I'm hopeful that we can resolve today's issues and have a better day tomorrow."