Ali leads the expert list — three heavyweight titles, the Rumble in the Jungle, the Thrilla in Manila. His combination of speed, power and ring intelligence has not been equalled. Rocky Marciano sits second on the expert list: 49 fights, 49 wins, retired undefeated, never seriously hurt. Joe Louis third — 25 consecutive title defences over 12 years. Tyson fourth: peak Tyson was the most physically frightening heavyweight who ever lived, but a career that unravelled after 1990 costs him a higher placement.