
15. Muhammad Ali (1978)
Ali suffered numerous defeats throughout his career. However, only one man was able to take his titles away inside the ring. That boxer was Leon Spinks. Spinks came into this fight as an Olympic gold medalist. But he only had six professional fights to his name. Needless to say, Ali was a massive favorite when they met in Las Vegas. But the bookmakers endured a hard day at the office.

This was the upset of the year. Spinks unsettled Ali and stayed game throughout the entire fight. Finally, the bout went to a decision. Two of the judges scored it in favor of Spinks while one gave it to the champion. Later, Ali reclaimed his titles in a rematch. He defeated Spinks by unanimous decision on that night. This was a tremendous result for his young opponent.