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, is a teacher and he has a younger sister named Julieta. Del Potro speaks Spanish and knows some Italian and English. Aside from tennis, he enjoys playing football and supports the Boca Juniors team in Argentina and Juventus in Italy. He would often dedicate time to both sports during his childhood, and Argentinian-Italian international footballer Mauro Camoranesi remains a close friend of del Potro. Del Potro began playing tennis at the age of seven with coach Marcelo Gómez (who also coached Tandil-born players Juan Mónaco, Mariano Zabaleta and Máximo González). Del Potro's talent was discovered by Italian ex-tennis professional Ugo Colombini, who accompanied him through the initial phases of his young career, and is still today his agent and close friend. questioned about his ambitions in tennis he replied, "I dream of winning a Grand Slam and the Davis Cup.
