Claiming his first belt at 20 years, four months, and 22 days old, Tyson holds the record as the youngest boxer ever to win a heavyweight title. He was the first heavyweight boxer to simultaneously hold the WBA, WBC and IBF titles, as well as the only heavyweight to unify them in succession. The following year, Tyson became the lineal champion when he knocked out Michael Spinks in 91 seconds of the first round.