His biggest achievement has been winning the 2009 US Open, defeating Rafael Nadal in the semifinal and 5-time defending champion Roger Federer in the final. He was the first to defeat both Federer and Nadal during the same major and was the only man outside the Big Four to win a major between the 2005 French Open and the 2013 US Open, a span of 35 tournaments. He is also the second Argentine and the fifth-youngest man to win the US Open in the Open Era. Other career highlights include winning the Indian Wells Masters in 2018, bronze medal in men's singles at the 2012 London Olympics and the silver medal at the 2016 Rio Olympics and being part of his country's successful Davis Cup team; but his career has also been hampered by a succession of wrist injuries.
Del Potro achieved a top-10 ranking by the Association of Tennis Professionals (ATP) for the first time on 6 October 2008. In January 2010, he reached a career-high ranking of world No. 4, after which del Potro had to withdraw from most of the tournaments in 2010 due to a right wrist injury. He returned in 2011 and was back to world No. 4 in January 2014 but had to withdraw from competition due to another wrist injury, but this time to his left wrist.
He returned to the ATP World Tour on 15 February 2016, at Delray Beach, after a long injury-induced absence. Later that year Del Potro gave two of the strongest performances of his career against Andy Murray - in the 2016 Summer Olympics he discovered a huge vein of form by defeating both Novak Djokovic, in straight sets in the first round, and Rafael Nadal, in the semi-finals, before falling in the final to Andy Murray in an attritional 4 sets. Only weeks later, the two men met again in the Davis Cup semi-final in Glasgow, Del Potro emerging victorious against Murray in 5 sets. He then led Argentina to a first-ever Davis Cup title by defeating Marin Cilic's Croatia in the Davis Cup Final in Zagreb. In 2018 he won the Indian Wells Masters singles title after defeating defending champion Roger Federer in the final.
Having started playing tennis at the age of seven, del Potro won his first senior match (ITF level) in 2004 at the age of 15. At the start of the 2006 season, at 17 years of age he notched his first ATP Tour match win against world No. 117, Albert Portas. In 2008, he became the first player in ATP history to win his first four career titles in as many tournaments. He also completed the second-longest winning streak in 2008, and the second longest by a teenager in the Open Era with his winning sequence spanning 23 matches over five tournaments, falling just one short of Rafael Nadal.
Juan Martín del Potro was born in Tandil, Argentina. His father, Daniel del Potro, played semi-professional rugby union in Argentina and is a veterinarian. His mother, Patricia Lucas, is a teacher and he has a younger sister named Julieta. He also had an elder sister who died when she was 8 years old in a car accident. Del Potro speaks Spanish, English and some Italian.