Mason, Ohio : Juan Martin del Potro didn't have to play a full set to advance at the Western & Southern Open. His next match will be a much tougher challenge.
The Argentine advanced against an injured Andreas Seppi on Sunday, setting up a second-round rematch with Roger Federer. Del Potro beat Federer in the 2009 U.S. Open final.
"If I have a good day, maybe I can make a surprise," said del Potro, currently ranked No. 19. "Not many players can beat Federer. I've already beaten him twice, so I know how to play him. But it's Roger. He's the favorite."