Guillermo Sebastián Coria, nicknamed El Mago, is an Argentine retired professional tennis player. He reached a career-high ATP world No. 3 singles ranking in May 2004. Coria achieved his best results on clay, where he won eight of his nine ATP singles titles, and during his prime years in 2003 and 2004 was considered "the world's best clay-court player." He reached the final of the 2004 French Open, where he was defeated by Gastón Gaudio despite serving for the match twice and being up two sets to love. In later years, injuries and a lack of confidence affected his game, and he retired in 2009 at the age of 27. Between 2001 and 2002, he served a seven-month suspension for taking the banned substance nandrolone.

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.