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
Boxing in Japan a member of each regional subsidiary body of Japan Pro Boxing Association under the Japan's conventional gym system. Two professional boxers belonging to the same gym have not been allowed to fight against each other unless one of them transfers to other gym, because it might disrupt the gym system. However, it is often quite difficult for boxers to transfer between the gyms due to the matters on transfer fees, match fees and so on. The JBC set up the Japanese heavyweight title once in 1957, but that division did not last long because there were few heavyweight boxers in