Mack enrolled at the University of Michigan in 1962 and played college football for Michigan Wolverines football teams from 1963 to 1965. As a sophomore in 1963, he played at the end position and spent most of the season on the bench. After the 1963 season, Mack switched to the tackle position at the suggestion of Michigan coach Bump Elliott. Mack later referred to the position change as "the big break of my life," an opportunity that "turned my whole experience in terms of football around."