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 Sunday, setting up a second-round rematch with Roger Federer. Del Potro beat Federer in the 2009 US 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.” They have faced each other eight times with del Potro winning the last two. Play began Sunday in the men's draw at the tournament, which combines the Cincinnati Women's Open and the Cincinnati Masters for the first time. In the evening session, James Blake advanced with a 3-6, 6-3, 6-2 victory over Marcos Baghdatis, avenging a five-set loss to him at this year's Wimbledon. The first day also produced some star power when golfer Rory McIlroy, who competed at the PGA Championship in Atlanta earlier in the day, was spotted watching girlfriend Caroline Wozniacki's practice session on court 15.
