Roger Federer says it's no coincidence that he has had so much success indoors. Until he lost to Juan Martin del Potro in last month's Basel final, he had not been beaten on an indoor hard court for two years.

"I think indoors is a natural surface for me,"  he told reporters. "So is clay actually, because those were the two surfaces I grew up on.  In the summers, I used to play on the clay courts outdoors, and in the winters, I played indoors on Supreme, carpet. When I was young I also had my first success on the tour actually indoors back in Marseille and Rotterdam and Basel and Toulouse.  Outdoors, I'm actually amazed how good I've become in the wind and humidity.  That, for me, was the tough part, actually becoming a good player in those conditions."