About 60,000 people filled the 20th of May Stadium in Kinshasa, Zaire, to see Muhammad Ali challenge heavyweight champion George Foreman. Foreman was the clear favorite.
Ali leaned on the ropes and let him punch himself out, a tactic he called "rope-a-dope". In the eighth round Ali put Foreman down with a left hook and a straight right, and the title was his again.
Source: Wikipedia