 De La Hoya defeated Arturo Gatti (33–4) by fifth-round TKO on March 24, 2001.He then moved up to light middleweight, challenging the lineal and WBC champion Javier Castillejo.De La Hoya dominated the fight, winning almost every round and knocking Castillejo (51–4) down with ten seconds to go to win the title by a unanimous decision.