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
Undisputed champion recognised a different champion. The disputes were usually short-lived as a lucrative fight would be organised between the rival champions. The longest split was ten years, of the middleweight title, between Mickey Walker's move up to heavyweight in 1931 and NBA champion Tony Zale's defeat of NYSAC contender Georgie Abrams in 1941. An early use of "undisputed" appears in a "New York Times" preview of the 1941 fight. The growing popularity of boxing outside of the USA led to creation of various boxing organizations, each strengthening their influence (most notably BBBofC) and having their own champion. This resulted in a