Guillermo Vilas

Guillermo Vilas (Spanish pronunciation: [ɡiʎeɾmo bilas]; born 17 August 1952) is an Argentine former professional tennis player. He was the world No. 1 of the Grand Prix seasons in 1974, 1975 and 1977. He won 62 singles titles and 16 doubles titles during his career, including four singles major titles and the 1974 Tour Finals. World Tennis, Agence France-Presse and Livre d'or du tennis 1977 (Christian Collin-Bernard Ficot), among other rankings and publications, rated him as world No. 1 in 1977. In the computerized ATP rankings, he peaked at No. 2 in April 1975, a position he held for a total of 83 weeks, although some have argued that Vilas should have been ranked No. 1 for at least 10 weeks, particularly in 1977 when he won two majors. He was inducted into the International Tennis Hall of Fame in 1991, two years after his first retirement.

Vilas is known for his prowess on clay courts. He won over 650 matches on clay, an all-time record. His peak was the 1977 season during which he won 16 ATP singles titles, including two majors (both on clay) and had a 53-match winning streak on clay, the longest in the Open Era at his time. In 2016, The Daily Telegraph ranked him as the third best male clay-court player of all time, behind Rafael Nadal and Björn Borg. In 2018, Steve Tignor for Tennis Magazine ranked him as the 16th greatest tennis player of the Open Era.

Historical and statistical studies presented in 2015 by Argentinian journalist Eduardo Puppo and Romanian mathematician Marian Ciulpan concluded that Vilas should have been No. 1 in the old ATP ranking system for seven weeks between 1975 and 1976. The ATP and its chief executive at that time, Chris Kermode, although not refuting the data, decided not to officially recognize Vilas as No. 1. In October 2020, Netflix released a documentary film about Vilas's case titled Guillermo Vilas: Settling the Score. In May 2024, ATP's vice-president confirmed that Vilas will never be number one.