Rubens' quit threat

The Brazilian has yet to finish ahead of the German so far this year with Renault's Jarno Trulli the only driver to get the better of Schumacher with his victory at the Monaco Grand Prix following the Ferrari driver's exit in the tunnel.

Barrichello insists he can still beat Schumacher, but he admits that if the day comes when he thinks this is no longer possible then he will hang up his helmet.

"When it comes to a point that I think I will never be able to out-race Michael then I will give up and do something else," he told The Sun."I have to come to each race believing I can beat him because I would have to retire if I didn't. There would be no fun for me any more. I won't be satisfied until I am in front of him. I've had poles and wins but I have to believe that I'm getting better and can fight Michael for the title.

"I'm driving against the best racer in the world," he added. "But it's no consolation coming second."

Barrichello is currently trailing Schumacher by 26 points in the drivers' standings with BAR-Honda's Jenson Button in third spot, 21 points adrift of the Brazilian.