Key fights in the boxing career of Muhammad Ali

IMAGE: Muhammad Ali flies around the ring after beating Sonny Liston in the seventh round of the World Heavyweight Title bout in Miami Beach. It was during these scenes that he claimed, 'I am the Greatest' and 'I shook up the World'. Photograph: Allsport Hulton/Archive.

Important bouts in the career of former heavyweight champion Muhammad Ali:

* Sept. 5, 1960 - Wins the Olympic light-heavyweight gold medal in Rome in a unanimous decision over Zbigniew Pietrzykowski of Poland.

* Oct. 29, 1960 - Makes his professional debut in his hometown of Louisville, Kentucky, winning a six-round unanimous decision over Tunney Hunsaker, whose day job was police chief of Fayetteville, West Virginia.

* Feb. 25, 1964 - Boasting a 19-0 record, wins the heavyweight title at age 22 by beating Sonny Liston, who surrenders after six rounds, in Miami Beach.

* March 22, 1967 - After eight successful title defenses, including another win over Liston and one over former champ Floyd Patterson, Ali knocks out Zora Folley in the seventh round in New York.

It was his last fight before losing his titles and facing prison for refusing to be inducted into the U.S. Army.

IMAGE: In a title fight at Madison Square Gardens, New York, Muhammad Ali goes down in the 15th round to a left hook from world heavyweight champion Joe Frazier who kept the title with an unanimous points win. Photograph: Keystone/Getty Images.

Oct. 26, 1970 - After a 3 1/2-year layoff due to his legal troubles, Ali returns to the ring in Atlanta against Jerry Quarry and wins by TKO in the third round.

* March 8, 1971 - Ali faces Joe Frazier, who had become heavyweight champ during Ali's hiatus, in a greatly anticipated match that promoters called the fight of the century in New York. Both men were undefeated going into the bout, which pitted Ali's speed and reach against Frazier's doggedness and stronger punching power. Ali started strong but Frazier dominated the latter part of the 15-round fight and won by unanimous decision.

* March 31, 1973 - Ali's second loss is a split decision against Ken Norton, who broke Ali's jaw. Six months later Ali wins a rematch with Norton.

* Jan. 28, 1974 - Ali beats Frazier, who had lost his title to George Foreman, by unanimous decision.

* Oct. 30, 1974 - Ali is a decided underdog going into the Rumble in the Jungle in Kinshasa, Zaire, against the fearsome and younger Foreman.

Instead of his usual dancing footwork, Ali spends much of the fight covering his face with his arms and leaning against the ropes in a strategy called the "rope-a-dope."

His plan is to let Foreman tire himself out by throwing punches that did no serious damage and it works, allowing Ali to knock him out in the eighth round and reclaim the major boxing championships.

IMAGE: American boxer Muhammad Ali addressing the crowd before his fight with Leon Spinks in New Orleans, in which Ali went on to regain the World Heavyweight title. Photograph: Keystone/Getty Images.

Oct. 1, 1975 - The second rematch with Frazier is called the Thrilla in Manila and part of the pre-fight hype includes Ali calling Frazier a gorilla. Ali wins when Frazier is unable to come out for the 15th and final round. The temperature approached 100 degrees (38 C) and Ali describes the fight as the closest he had come to death.

* Feb. 15, 1978 - Ali, now 36, loses his titles by split decision to Leon Spinks, 25, who had only seven professional fights after winning a gold medal in the 1976 Olympics.

* Sept. 15, 1978 - Ali gets the a heavyweight title back by beating Spinks in a 15-round unanimous decision, making him the first man to reign as champion three times. He then retires.

* Oct. 2, 1980 - At age 38 he attempts a comeback in a title fight against Larry Holmes, a former Ali sparring partner, but his skills are clearly eroded. Ali's trainer stops the fight after 10 rounds, marking the only time in his career that Ali lost by anything other than a decision.

* Dec. 11, 1981 - Ali's final fight is a unanimous decision loss to Trevor Berbick.