Roger Federer of Switzerland returns to John Isner of the United States at the All England Lawn Tennis Club in Wimbledon, London at the 2012 Summer Olympics, Thursday, Aug. 2, 2012. (AP Photo/Elise Amendola)
Bobby Reynolds of the United States plays a shot in his match against fellow countryman John Isner on the fourth day of play at the Sydney International tennis tournament in Sydney, Australia, Wednesday, Jan. 11, 2012. (AP Photo/Rob Griffith)
John Isner became the last American man to be eliminated when Paul-Henri Mathieu outlasted him 18-16 in the fifth set. The 5 hour, 41 minute match was the second-longest in French Open history. (Associated Press)
U.S. team player John Isner reacts after winning his match against France's Gilles Simon in the quarterfinal of the Davis Cup between France and U.S. in Monaco on Friday, April 6, 2012.(AP Photo/Remy de la Mauviniere)
John Isner, of the United States, returns a shot to Novak Djokovic, of Serbia, during a men's semifinal match at the BNP Paribas Open tennis tournament Saturday, March 17, 2012, in Indian Wells, Calif. (AP Photo/Darron Cummings)
US Davis Cup tennis player John Isner reacts after he defeated Swiss Davis Cup player Roger Federer during a Davis Cup World Group first-round second match between Switzerland and the US in the Forum Arena in Fribourg, Switzerland, Friday, Feb. 10, 2012. (AP Photo/Keystone/Laurent Gillieron)
John Isner of the US lost to Spain's Feliciano Lopez at the Australian Open in Melbourne, Australia, 6-3, 6-7 (3), 6-4, 6-7 (0), 6-1. (AP Photo/Rick Rycroft)
John Isner acknowledges the crowd after defeating James Blake 7-6 (0), 1-6, 7-6 (4) at the Legg Mason Tennis Classic on Thursday. (AP Photo/Luis M. Alvarez)
John Isner moved onto the final at the Atlanta Tennis Championships for the third straight year with his win against Gilles Muller on Saturday. (AP Photo/Elise Amendola)
John Isner moved onto the final at the Atlanta Tennis Championships for the third straight year with his win against Gilles Muller on Saturday. (AP Photo/Elise Amendola)
** FILE ** In this July 25, 2010, file photo, Mardy Fish reacts after defeating John Isner, 4-6, 6-4, 7-6 (7-4) in the finals of the Atlanta Tennis Championships tennis tournament in John's Creek, Ga. (AP Photo/John Bazemore, file)
John Isner, playing a doubles match with James Blake, returns a shot against their opponents Robby Ginepri and Ryan Sweeting during the Atlanta Tennis Championships on Monday, July 19, 2010, in Atlanta. (AP Photo/Atlanta Journal Constitution, Curtis Compton)
John Isner of the US reacts to a lost point during his match against Thiemo de Bakker of Netherland's at the All England Lawn Tennis Championships at Wimbledon, Friday, June 25, 2010. (AP Photo/Mark Baker)
John Isner of the US, left, and Nicolas Mahut of France, right, talk with chair umpire Mohamed Lahyani before resuming their their epic men's singles match at the All England Lawn Tennis Championships at Wimbledon on Thursday, June 24, 2010. The match was resumed with the sores tied at 59 all in the fifth set. (AP Photo/Alastair Grant)
John Isner of the US, left, smiles at Nicolas Mahut of France as he lies on the court during their epic men's singles match at the All England Lawn Tennis Championships at Wimbledon, Wednesday, June 23, 2010. Play was suspended for bad light with scores tied at 59 all in the 5th set. (AP Photo/Mark Baker)