John Isner celebrates after upsetting top seeded Novak Djokovic, from Serbia, 7-6 (5), 3-6, 7-5, in a quarterfinal match at the Western & Southern Open tennis tournament, Friday, Aug. 16, 2013, in Mason, Ohio. (AP Photo/Al Behrman)

Photo by: Al Behrman

John Isner celebrates after upsetting top seeded Novak Djokovic, from Serbia, 7-6 (5), 3-6, 7-5, in a quarterfinal match at the Western & Southern Open tennis tournament, Friday, Aug. 16, 2013, in Mason, Ohio. (AP Photo/Al Behrman)