Mike Tyson became a professional boxer in 1985 and won a heavyweight title from Trevor Berbick in 1986. He was the youngest man to win a heavyweight title belt. He became recognized as the undisputed champion when he beat Michael Spinks in 1988. He lost his title to Buster Douglas in 1990. Tyson won his first 19 professional bouts by knockout, 12 of them in the first round. 