Muhammad Ali‘s resume includes plenty of the most legendary fighters to have ever lived.

The American boxer and social activist fought 61 times in all across a storied career that was divided into two chapters separated by his refusal to be drafted to the army in 1967. His boxing license and world title were stripped, and the decision was not overturned until 1971, which many believe cost him the best years of his career.

Three years after his return came his most famous battle, The Rumble in the Jungle in Zaire with heavyweight champion George Foreman, whom he beat, and a year later he took part in the Thrilla in Manila to conclude his trilogy with Joe Frazier with another win. Ali also beat the likes of Ron Lyle, Ken Norton and Leon Spinks before losing to Larry Holmes and Trevor Berwick in his last two fights and retiring in 1981.

In quotes that have recently resurfaced, Ali named Brit heavyweight legend Henry Cooper as the toughest fighter he ever faced.

“Cooper’s not a bum anymore. I underestimated him. He’s the toughest fighter I ever met [in the ring] and the first to really drop me. He’s a real fighter.”

He also credited him with having great, lasting power.

“That left hook that Cooper hit me with didn’t only shake me, it shook my relations in Africa.”

The pair fought twice in London – first in 1963, then again 1966, with Ali winning by KO both times, though in the first contest he was put down by a left hook and saved by the bell at the end of the fourth round.

Cooper finished with a record of 40 wins, 14 defeats and 1 draw, winning the British, Commonwealth and European heavyweight title during his career.