Soon after he won his Olympic medal Ali became a professional boxer. During his career he had sixty-on fights against the best boxers in the world, and lost only five of them. In February 1964 he beat Sonny Liston to become the heavyweight boxing champion of the world. In fact, Ali didn't lose a fight until 1971, when he was beaten by Joe Frazier. Ali was an amazing boxer. He was fast, skillful and entertaining. He was also very funny. He made up poem and jokes about his opponent.