16. Ali vs. Liston II (1965):
Cassius Clay stunned the world when he forced Sonny Liston to retire on his stool. The new heavyweight champion agreed to defend his title in a rematch. This became one of the most controversial fights of all time. Clay won by knockout after Liston went down in the first round. However, the blow shouldn’t have resulted in a finish. An enraged Clay stood over Liston and told him to get up.

Many believe that the mafia forced Liston to throw the fight because of debts. It effectively ended Liston’s career and he died just five years later in dark circumstances. The entire rivalry was controversial because Liston allegedly tried to blind Clay in the first fight. He rubbed a substance on his gloves but it didn’t help. Ali then went on to achieve greatness beyond his wildest dreams.