Lleyton Glynn Hewitt is an Australian former world No. 1 tennis player. He is the most recent Australian man to win a major singles title, at the 2001 US Open and 2002 Wimbledon Championships. In November 2001, Hewitt became, at the time, the youngest man to reach No. 1 in the ATP singles rankings, at the age of 20 years, 8 months and 26 days. In total, he won 30 singles titles and 3 doubles titles, including the 2000 US Open men's doubles title, back-to-back Tour Finals titles in 2001 and 2002, and the Davis Cup with Australia in 1999 and 2003. Between 1997 and 2016, Hewitt contested a record twenty consecutive Australian Open men's singles tournaments, his best result being runner-up in 2005. He was also the runner-up at the 2004 US Open.

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.