Heavyweight unification series 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 to crown an undisputed champion of the heavyweight class. The series was produced by HBO Sports and promoted by Don King. It ended with Mike Tyson as undisputed champion, holding the championship belts of the International Boxing Federation, World Boxing Association, and World Boxing Council. Prior to the series, the last undisputed heavyweight champion had been Leon Spinks, who won the championship in his 1978 victory over Muhammad Ali. Spinks had been stripped of
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