Juan Martín del Potro (Spanish pronunciation: [xwam maɾˈtin del ˈpotɾo]; born 23 September 1988) is an Argentine former professional tennis player. Del Potro's biggest achievement was a major title at the 2009 US Open, where he defeated Rafael Nadal and the five-time defending champion Roger Federer en route. Del Potro's other career highlights include reaching the 2018 US Open final, winning an Olympic silver medal at the 2016 Rio Olympics and a bronze medal at the 2012 London Olympics, winning Indian Wells in 2018, and leading Argentina to the 2016 Davis Cup title. Del Potro won 22 ATP singles titles and one doubles title during his career. Notably, his career was hampered by a succession of wrist and knee injuries.

Del Potro first entered the top 10 of the ATP rankings on 6 October 2008. With his US Open win, he became the only man outside the Big Three (Nadal, Federer, and Novak Djokovic) to win a major between the 2005 Australian Open and the 2012 US Open, a span of 30 tournaments. In January 2010, he reached a then-career-high ranking of world No. 4, after which he withdrew from most of the season due to an injury to his right wrist. In 2016, del Potro led Argentina to its first Davis Cup title by defeating Croatia's Marin Čilić in the final from two sets down. He then reached his first major semifinal in four years by defeating Federer in the quarterfinals of the 2017 US Open. In 2018, he won his first Masters 1000 title at Indian Wells, defeating the defending champion and world No. 1 Federer in the final. After reaching the semifinals of the 2018 French Open, he matched his career-high ranking of No. 4, and in August 2018 he reached the world No. 3 ranking for the first time. At the 2018 US Open, he reached his second major final, where he lost to Djokovic. Del Potro did not play between June 2019 and February 2022 because of pain from a knee injury, ultimately retiring in 2024 after a farewell exhibition match against Djokovic.