Top-seeded Andy Roddick lost to Juan Martin del Potro in the Legg Mason Tennis Classic final in Washington, falling, 3-6, 7-5, 7-6 (6), to the defending champion.

The winning shot on Sunday came on a crosscourt forehand. The replay system on Roddick’s challenge confirmed the ball hit the outer portion of the sideline, and del Potro raised both arms above his head in celebration.

It was the first loss for Roddick in four Washington finals. Roddick won the tournament in 2001, 2005 and 2007.

This was Roddick’s first tournament since losing an epic Wimbledon final to Roger Federer on July 5. Roddick had taken a monthlong break to recover from a right hip flexor injury.

In women’s play, Flavia Pennetta took advantage of error-prone Samantha Stosur for a 6-4, 6-3 victory in the LA Women’s Tennis Championships in Carson, Calif.