A supremely confident Andy Schleck says it's a matter of 'when', not 'if', he or his brother will win the Tour de France after a strong ride on Stage 12 put him and Frank ahead of their GC rivals.

"Everybody who's dangerous in the GC, I'm happy when they lose time in the mountains," Schleck said after gaining time over the likes of Alberto Contador and Levi Leipheimer on the day. "It means we're doing things right."

And asked whether he would feel slighted should brother Frank grab the yellow jersey ahead of him, Schleck was in diplomatic mood.

"I would like to win the Tour but if my brother wins the Tour I'll be as happy as if I had," he said. "The question is not if we can win the tour, but how can we."

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