Ali hailed fellow American Robinson as the Greatest Of All Time and pound-for-pound best after he retired following his unanimous decision loss to Joey Archer at Civic Arena in Pittsburgh in 1965.
Robinson, real name Walker Smith Jr, died in April 1989 but was posthumously inducted into the Hall of Fame in 1990.
Between 1943 and 1951 the American went on a 91-fight unbeaten streak before he eventually lost to Randolph Turpin.
After the loss, Robinson won his rematch with Turpin via technical knockout, but he was arguably never the same again after that.
Robinson’s most notable wins came against Henry Armstrong, Rocky Graziano, Jake LaMotta and Bobo Olson.
He is widely regarded as one of the greatest fighters of his generation.
Like Robinson, Ali himself is often acclaimed as the GOAT.
However, he insisted that he did not deserve such recognition during a candid interview which was recently uploaded to social media by Twitter user @BoxingHistory.
And even though many consider the four-time world champion as the best ever, he considered Robinson, the man who he idolised as a child growing up on the streets of Louisville, the greatest.
WATCH: Muhammad Ali explains why ‘Sugar’ Ray Robinson is the greatest
Check out the video below…
In the clip, Ali says: “To me, in his time, and even today, the pound for pound, when they say ‘Sugar’ Ray Robinson was the greatest fighter pound for pound, meaning that if I’d imagine he was a heavyweight fighting the same style, he’d be the greatest.
“I would have to admit, I would have to say yes, Robinson is the greatest of all time.
“I have his fight films, I watched them then, you have them.
“That man was beautiful. Timing, speed, reflexes, rhythm, his body. Everything was beautiful.
“And to me, still, I would say pound-for-pound I would say I’m the greatest heavyweight of all time, but pound-for-pound I still say ‘Sugar’ Ray Robinson was the greatest of all time.
“All records are broken. Hank Aaron… Babe Ruth’s record got broken. Jesse Owens… All kinds of records are broken.
“But I wanna see somebody beat ‘Sugar’ Ray’s record. Nobody yet has beaten his record.”