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
Scott Gammer once again when he boxed John McDermott later that year in an elimination bout. The contest took place in Sheffield but ended up with another defeat for the Welshman. Following this setback Gammer announced his retirement from boxing and McDermott went on to challenge for the title. The retirement did not last that long however as Gammer returned to action in August 2008 when he challenged Francesco Pianeta for the EU Heavyweight championship in Germany. The fight ended with another defeat for Gammer, although this time it was due to a corner retirement when Gammer broke his hand in the