Frazier won the vacant world heavyweight title by beating Buster Mathis. He lost the title to George Foreman whom had knocked out Frazier in a 3 punch combo, breaking his eye socket, jaw, and collar bone. Frazier's most famous fights were rematches with Muhammad Ali. He beat Ali in their first fight in 1971 but lost the other two. The third fight was known as the "Thrilla in Manila".