Ryan Harrison of the US hits a return against compatriot John Isner during their match at the Sydney International tennis tournament on January 9, 2013. AFP PHOTO / MANAN VATSYAYANA
Credit: MANAN VATSYAYANA
John Isner celebrates match point against Juan Martin Del Potro of Argentina during the semifinals of the Western & Southern Open on August 17, 2013 at Lindner Family Tennis Center in Cincinnati, Ohio.
Credit: Matthew Stockman
John Isner of the United States prepares to serve during his Gentlemen's Singles third round match against Feliciano Lopez of Spain on day seven of the Wimbledon Lawn Tennis Championships at the All England Lawn Tennis and Croquet Club on June 30, 2014 in London, England.
Credit: Jan Kruger
John Isner of the USA holds the trophy after his win over Yen-Hsun Lu of Chinese Tapei during the final of the Heineken Open at the ASB Tennis Centre on January 11, 2014 in Auckland, New Zealand.
Credit: Sandra Mu
John Isner of the USA serves in his semi final match against Roberto Bautista Agut of Spain during day five of the Heineken Open at the ASB Tennis Centre on January 10, 2014 in Auckland, New Zealand.
Credit: Phil Walter
John Isner of the United States reacts after defeating Jan-Lennard Struff of Germany during their men's singles second round match on Day Four of the 2014 US Open at the USTA Billie Jean King National Tennis Center on August 28, 2014 in the Flushing neighborhood of the Queens borough of New York City.
Credit: Streeter Lecka
John Isner of the United States serves during his match against James Ward of Great Britain during day three of the 2015 Priceline Pharmacy Classic at Kooyong on January 15, 2015 in Melbourne, Australia.