Kevin McBride McBride's career-defining performance was a victory over Mike Tyson, former undisputed world heavyweight champion, via a 6th-round TKO on 11 June 2005 when Tyson quit the fight by informing the referee that he would not be able to continue to round Seven in the MCI Center in Washington, D.C. The aged Tyson explained in a post fight interview that his heart wasn't into the sport any more. Tyson announced his retirement after the bout, saying "I'm not going to disrespect the sport anymore by losing to this caliber of fighter". McBride has suffered six losses by knockout—including twice against fighters
Heavyweight unification series Following the unification series, there were ongoing calls for Tyson and Spinks to fight, to erase any doubt about the identity of the "true" champion. In June 1988, the two champions faced off, and Tyson knocked out Spinks in 91 seconds. Tyson held on to his titles until February 1990, when he was knocked out by Buster Douglas. The titles remained unified until December 1992, when undisputed champion Riddick Bowe relinquished his WBC title. Heavyweight unification series The heavyweight unification series, also known as the Heavyweight World Series, was a sequence of professional boxing matches held in 1986 and 1987