On this date in 1964, the 22-year-old, Louisville, Kentucky born Cassius Clay, also known as Muhammad Ali, became world heavyweight boxing champion by defeating Sonny Liston in a stunning upset. At the height of his athletic career Ali was well known for both his fighting ability and personal style. His most famous saying was “I am the greatest!” Ali is the only fighter to win the heavyweight fighting title three separate times – 1964, 1974, and 1978. He defended his title nine times.