Mac won a gold medal for Canada in the Olympics. He went on to fight professionally, and soon became a #1 contender. He was scheduled to fight Apollo Creed, but due to injury, had to pull out of the fight, leaving the "Master Of Disaster" to find a new opponent. With a still weak hand he fought a month and a half later and went on a losing streak of 5, including a loss against Rocky Balboa.
Green made a comeback in 1982 by beating Buddy Shaw. He went on to challenge Union Cane for the vacant Heavyweight title after Rocky Balboa retired, but was soundly defeated in round two.