Going into the French Open in 2002, Costa had not won a tour title of any kind since 1999 and was not considered to be among the favorites. Seeding 20th, he defeated Richard Gasquet, Nikolay Davydenko and Andrea Gaudenzi to reach the fourth round, where he defeated two time defending-champion and former world No. 1 Gustavo Kuerten in straight sets. He followed up with a five-set victory over Argentina's Guillermo Cañas in a quarterfinal. He then defeated fellow-Spaniard, former world No. 2 and long-time friend Àlex Corretja in a four-set semifinal. In the final, Costa came up against another Spaniard, future world No. 1, Juan Carlos Ferrero. Ferrero had been in fine form in the run-up to the event and most observers considered him to be the heavy favourite going into the final. But Costa won in four sets, 6–1, 6–0, 4–6, 6–3, to claim his first Grand Slam title. Costa destroyed Ferrero, who could only win nine points during Costa's service games in the first 2 sets. The win propelled him to his career-high singles ranking of World No. 6 in July 2002.