Mike Tyson is a former undisputed heavyweight champion of the world and holds the record as the youngest boxer to win the WBC, WBA and IBF heavyweight titles at 20 years, 4 months, and 22 days old. Tyson won his first 19 professional bouts by knockout, 12 of them in the first round. He won the WBC title in 1986 after defeating Trevor Berbick by a TKO in the second round. In 1987, Tyson added the WBA and IBF titles after defeating James Smith and Tony Tucker. He was the first heavyweight boxer to simultaneously hold the WBA, WBC and IBF titles, and the only heavyweight to successively unify them.