John Robert Isner is an American former professional tennis player renowned for his powerful serve and commanding presence on the ATP Tour. A right-handed player with a two-handed backhand, Isner achieved a career-high singles ranking of World No. 8 and a doubles ranking of No. 14. He reached the quarterfinals at the 2012 Olympic Games, highlighting his success on the international stage. Known for his dominance in long matches and proficiency on hard courts, Isner secured multiple ATP singles and doubles titles throughout his career. He remains a respected figure and influential ambassador for American tennis worldwide.