Dominic Thiem is an Austrian professional tennis player. He has been ranked as high as world No. 3 in singles by the Association of Tennis Professionals, which he first achieved in March 2020. Thiem has won 17 ATP Tour singles titles, including a Grand Slam title at the 2020 US Open where he came back from two sets down to defeat Alexander Zverev in the final. With the win, Thiem became the first male player born in the 1990s to claim a Major singles title, as well as the first Austrian to win the US Open singles title. He had previously reached three other Major finals, finishing runner-up at the 2018 and 2019 French Open to Rafael Nadal, and at the 2020 Australian Open to Novak Djokovic. Thiem was also runner-up at the 2019 and 2020 ATP Finals, where he lost to Stefanos Tsitsipas and Daniil Medvedev, respectively.

The PIF ATP Rankings are the merit-based method used by the Association of Tennis Professionals (ATP) for determining the qualification for entry as well as the seeding of players in all singles and doubles tournaments. The first rankings for singles were published on 23 August 1973 while the doubles players were ranked for the first time on 1 March 1976. Ranking points are awarded according to the stage of tournament reached, and the prestige of the tournament, with the four Grand Slam tournaments awarding the most points. The rankings are updated every Monday, and points are dropped 52 weeks after being awarded. Novak Djokovic is the current men's singles world No. 1.