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John Isner

John Isner is an American former professional tennis player known for his powerful serve and exceptional height.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

John Isner is an American former professional tennis player known for his powerful serve and exceptional height. He reached a career-high singles ranking of world No. 8 and won 16 ATP singles titles before retiring after the 2023 US Open.

Early life and college career

John Isner was born in Greensboro, North Carolina, and began playing tennis at age nine. He played college tennis for the University of Georgia before turning professional in 2007.

Professional career

Isner competed on the ATP Tour from 2007 to 2023 and won 16 singles titles and 8 doubles titles. He reached a career-high singles ranking of No. 8 and was the top-ranked American for multiple seasons in the 2010s.

Playing style and records

Isner was widely recognized for his serve, which produced a record number of aces over his career. He is the ATP Tour’s all-time ace leader, with 14,470 aces. He is also closely associated with the longest match in tennis history, played at Wimbledon in 2010 against Nicolas Mahut.

Retirement

Isner announced the end of his career following the 2023 US Open, where he played his final singles match. His retirement marked the end of a long ATP career defined by serve-dominant play and consistency.

Key facts

  • Isner was one of the tallest players in top-level men’s tennis, listed at 6 ft 10 in (2.08 m).
  • He won 16 ATP singles titles and 8 ATP doubles titles.
  • His career-high ATP singles ranking was world No. 8 in 2018.
  • He is the ATP Tour’s all-time ace leader, with 14,470 aces.
  • He retired from professional tennis after the 2023 US Open.
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Canadian context

John Isner’s career is relevant to Canadian tennis fans because he competed regularly on the ATP Tour and at Canadian events, including major North American hard-court tournaments such as Toronto and Montreal as part of the tour calendar.

Frequently asked questions

Who is John Isner?
John Isner is an American former professional tennis player best known for his serve, height, and ATP Tour success.
What was John Isner’s highest singles ranking?
He reached a career-high singles ranking of world No. 8 in 2018.
How many ATP singles titles did John Isner win?
He won 16 ATP singles titles.
What is John Isner known for?
He is known for his powerful serve, record ace totals, and participation in the longest match in tennis history at Wimbledon in 2010.
When did John Isner retire?
He retired from professional tennis after the 2023 US Open.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/John_Isner
    Supports: Birth name, birth date, nationality, career-high singles ranking, retirement status, and general biography.
  2. ATP Tour — https://www.atptour.com/en/news/isner-retirement-feature-2023
    Supports: Retirement timing, ace total, career wins, ranking consistency, and career overview.
  3. Roland Garros — https://www.rolandgarros.com/en-us/players/15820-j.isner
    Supports: Height, handedness, turned pro date, titles, rankings, prize money, and win-loss record.
  4. Laver Cup — https://lavercup.com/player/john-isner
    Supports: Career-high ranking, birthplace, height, college background, family details, and title count.
  5. International Tennis Federation — https://www.itftennis.com/en/players/john-isner/800233503/usa/mt/D/overview/
    Supports: Age, handedness, preferred surface, and age started playing tennis.