Del Potro qualified for the main draw of his first Grand Slam in the 2006 French Open at the age of 17. He lost in the opening round to former French Open champion and 24th seed Juan Carlos Ferrero. Having received a wild card, he reached the quarterfinals of the ATP event in Umag, Croatia, where he lost in three sets to the eventual champion, Stanislas Wawrinka. In Spain, he participated in the Open Castilla y León Challenger tournament held in Segovia, defeating top seed Fernando Verdasco in the quarterfinals and Benjamin Becker in the final.