Ken Norton once regarded a former rival as the greatest heavyweight boxer of all time and said punching him was like “hitting a block of concrete”.

The former heavyweight champion of the world is perhaps best known for delivering split decisions against his opponents Muhammad Ali in 1973, then lost in an immediate rematch and a third meeting three years later.

Like Ali, though, the Americans also fell out with him. George Foreman, Larry Holmes And Ernie Shavers, they all got the better of him in one way or another.

For example, his clash with Foreman ended in a devastating second-round finish some seven months before the knockout artist’s fight. The iconic jungle fight with Ali.

The fight with Holmes was a much more competitive 15-round affair, with Norton losing a split decision and then getting knocked out — in the first round, no less — by Shavers after two fights.

Although Norton faced a formidable array of heavyweights, most of whom were in their prime, his trilogy with Ali was ultimately enough to determine who he considered the best.

talk with ESPN Radio Before his death in 2013, the Jacksonville man maintained that Ali was also the toughest opponent he had ever faced, justifying his emphasis on Ali being the greatest heavyweight boxer of all time.

“As far as I know, yes (Ali is the best of all time). Ali was very powerful, but because he was not a one-punch KO artist, (his power) was overlooked. Hitting Ali’s body or arms was like hitting a block of cement.”

The fact that Norton fought Ali and Foreman shortly before they met in 1974 should suggest that he knew what these two heavyweights were capable of better than most.

Not only that, but especially a total of 39 rounds with Ali, it will make Norton deeply realize how great he really is.