The two fighters continued with the same fighting style that they had used in the first fight, trading inside punches throughout the first three rounds. Early in the fourth round, Castillo knocked down Corrales with a left hook to his chin. Corrales wobbled to his feet at the referee's count of ten, causing the fight to end. Corrales vs. Castillo III, dubbed "The War to Settle the Score," had been scheduled for February 4, 2006, but it was postponed because of a rib injury that Corrales suffered while training. The fight was rescheduled for June 3, 2006. At the weigh-in, however, Corrales weighed the lightweight limit whereas Castillo weighed 139½ lb—causing the fight to be cancelled. Corrales later sued Castillo for punitive damages. Light welterweight On January 20, 2007, Castillo won a narrow split decision over Herman Ngoudjo. On June 23, he fought Ricky Hatton in Las Vegas. Castillo was KO'd 2 minutes and 16 seconds into the fourth round by a crunching left hook to the ribs, one of the few times a top ranked boxer of Castillo's caliber has been KO'ed by a bodyshot and reminiscent of the bout between Roy Jones Jr. and Virgil Hill. Prior to the knockout Castillo had been deducted a point for low blows to his opponent. Castillo was scheduled to fight Timothy Bradley in 2008 for the right to be number 1 contender to the WBC Super lightweight title, but during the weigh-in on March 8, 2008, Castillo weighed 147½ pounds (7 pounds over the super-lightweight limit). Bradley instead faced and defeated Junior Witter for the title. Welterweight On the Pacquiao vs Clottey undercard on March 14, 2010, Alfonso Gomez and Castillo clashed for Gomez' WBC Continental Americas welterweight title. Ringside reporters have said that the fight was to see if Castillo had it anymore, and for this type of fight such a minor title is nearly an insult. Castillo lost in round 5 by TKO (not answering to the bell). After the bout Castillo announced his retirement, stating, "I just found out tonight I don't have it anymore, I want to apologize to the public and I am definitely announcing my retirement." After announcing his retirement in March 2010, Castillo returned to action in a fight against Roberto Valenzuela on June 18, 2010 and won the bout by unanimous decision. The match was held at the Auditorio Municipal in Tijuana, Baja