From Wikipedia:
In one of the biggest upsets in boxing history, Ali regained his title on October 30, 1974 by defeating champion George Foreman in their bout in Kinshasa, Zaire. Hyped as “The Rumble In The Jungle,” the fight was promoted by Don King. Almost no one, not even Ali's long-time supporter Howard Cosell, gave the former champion a chance of winning. Analysts pointed out that Joe Frazier and Ken Norton had given Ali four tough battles in the ring and won two of them, while Foreman had knocked out both of them in the second round. As a matter of fact, so total was the domination that, in their bout, Foreman had knocked down Frazier an incredible six times in only four minutes and 25 seconds.
During the bout, Ali employed an unexpected strategy. Leading up to the fight, he had declared he was going to “dance” and use his speed to keep away from Foreman and outbox him. However, in the first round, Ali headed straight for the champion and began scoring with a right hand lead, clearly surprising Foreman. Ali caught Foreman nine times in the first round with this technique but failed to knock him out. He then decided to take advantage of the young champion's weakness: staying power. Foreman had won 37 of his 40 bouts by knockout, mostly within three rounds. Eight of his previous bouts didn't go past the second round. Ali saw an opportunity to outlast Foreman, and capitalized on it.
In the second round, the challenger retreated to the ropes—inviting Foreman to hit him, while counterpunching and verbally taunting the younger man. Ali's plan was to enrage Foreman and absorb his best blows to exhaust him mentally and physically. While Foreman threw wide shots to Ali's body, Ali countered with stinging straight punches to Foreman's head. Foreman threw hundreds of punches in seven rounds, but with decreasing technique and potency. Ali's tactic of leaning on the ropes, covering up, and absorbing ineffective body shots was later termed “The Rope-A-Dope.” By the end of the seventh round, Foreman was exhausted. In the eighth round, Ali dropped Foreman with a combination at center ring and Foreman failed to make the count. Against the odds, Ali had regained the title. Many years later, Foreman would become champ again at age 45. Muhammad Ali (Foreman's best friend at the time) did not attend the title bout. When asked why, he said “I would deviate attention from George. It was his moment, not mine.”
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Some of his famous quotes:
I wish people would love everybody else the way they love me. It would be a better world.
At home I am a nice guy: but I don't want the world to know. Humble people, I've found, don't get very far.I figure I'll be champ for about ten years and then I'll let my brother take over – like the Kennedys down in Washington.
Frazier is so ugly that he should donate his face to the US Bureau of Wild Life.