Guillermo Vilas (Spanish pronunciation: [ɣiˈʃeɾmo ˈbilas]; born 17 August 1952, in Buenos Aires, Argentina) is a retired professional tennis player from Argentina who won four major singles titles. Known for his prolific match play, especially on clay, he became the second man to win more than 900 matches in the Open Era, and his 660 wins on clay are by far the most of the era. His peak was the 1977 season during which he won two major titles (both on clay), had two long match win streaks of 46 all-surface and 53 on clay, and finished with an Open Era record 134 match wins. He also was the creator of the tweener shot.
A left-handed baseliner, Vilas's best year on tour was 1977 when he won two of the four Grand Slam singles tournaments and 16 of the 31 Association of Tennis Professionals tournaments he entered. His playing record for 1977 was 145 wins against 15 losses (ATP win-loss record was 130–15). Not including the Masters year-end championship, he won 72 of his last 73 ATP matches in 1977. The highest point during this phenomenal run was winning the last US Open played at Forest Hills against Jimmy Connors 2–6, 6–3, 7–6, 6–0 in a match where Vilas surprised his American rival by attacking the net.
Winning streak, most titles in a single year
In 1977 he won seven consecutive titles after Wimbledon – Kitzbühel (clay), Washington (clay), Louisville (clay), South Orange (clay), Columbus (clay), US Open (clay) and Paris (clay) – and set up a 46-match all-surface winning streak, third all-time behind Björn Borg's records of 49 and 48 consecutive matches won. He also had a record 57-match winning streak on clay courts (including both Association of Tennis Professionals (ATP) and unofficial tournaments), which stood until the record was broken by Rafael Nadal in 2006. Both his winning streaks were terminated in October 1977 by Ilie Năstase in the final of the Aix-en-Provence tournament. In that best of five-set final, Vilas dropped the first two sets by 6–1, 7–5 and then retired in protest of Năstase's use of a spaghetti strung racquet (which was banned shortly after by the ATP). After that he won a further 28 matches in a row with titles at Tehran, Bogotá, Santiago, Buenos Aires (all on clay) and Johannesburg (hard). That run was ended in the Masters semifinals by Björn Borg
Even though he won 16 ATP singles titles, including the French Open and the US Open and was the runner-up at the January edition of the Australian Open in 1977, he was never ranked by the ATP as World No. 1 during 1977. He was instead year-end World No. 2 in those rankings, below Jimmy Connors (who won the Masters and six other titles and was the runner-up at Wimbledon and the US Open in 1977). There is some controversy regarding his status as No. 2 ranked player for that year, but no official statement has been given by ATP.
Held the open era male record for the longest winning streak on clay courts at 53 matches, set in 1977, until it was bettered by Rafael Nadal in 2006. Nadal later extended this to 81 matches.
Won 62 ATP singles titles (eighth highest during the open era) and was the runner-up in 40 singles tournaments (plus two unfinished finals). Won 16 doubles titles with other 10 doubles finals.
He took Argentina to its first-ever Davis Cup final in 1981 (lost to the United States), together with José Luis Clerc, who was also a top-ten player. The Argentine press often referred to the tensions between the two of them, which even reverberated to the 2004 French Open awards ceremony, in which Vilas presented Gastón Gaudio with his trophy over Clerc's objections.
Vilas's success on the court led to a surge in popularity of tennis in Argentina and throughout Latin America. Guillermo Cañas and Guillermo Coria were named after him.