Juan Martín del Potro (Spanish pronunciation: born 23 September 1988) is an Argentine professional tennis player who is the current highest-ranked Argentine and the seventh-ranked player in the world. Del Potro achieved a top 10 ranking by the Association of Tennis Professionals for the first time on October 6, 2008. In January 2010, he reached a career-high ranking of World No. 4.
Having started playing tennis at the age of seven, del Potro won his first senior match in 2004 at the age of 15. 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, behind Rafael Nadal—with his winning sequence spanning 23 matches over five tournaments. Del Potro captured his maiden Grand Slam title at the 2009 US Open defeating Roger Federer in the final, and Nadal in the semifinal, becoming the first man ever to beat both Federer and Nadal in the same Grand Slam. He became the second Argentine and the fifth youngest man to win the US Open title in the Open Era.Later that year he qualified for the 2009 Barclays ATP World Tour Finals where he was the runner-up.
Source : Wikipedia.com