Even the legendary Muhammad Ali would have struggled against a "huge guy" like WBC world heavyweight champion Tyson Fury, says Bob Arum, who has managed both men.
In a star-studded promoting career, Top Rank's Arum helped bring Ali to Highbury Stadium in 1966, where he defeated British great Henry Cooper in a rematch from their first bout three years previously.
Arum has also been promoting Fury in the United States and the 'Gypsy King' ascended back to the top of the heavyweight division with a phenomenal victory over Deontay Wilder earlier this year.
The promoter also helped forge George Foreman's path to becoming the oldest ever heavyweight champion at the age of 45 in 1994 after he had spent 10 years away from the ring earlier in his career.
In an interview with Sky Sports, the 88-year-old Arum discussed the biggest names he has promoted and pondered what would have happened if Ali and Fury had ever mixed it in the ring.
"I look at Ali, I look at Foreman when he won the title when he was 45, I look at Fury," Arum said.
"How would Ali have done with Fury? That's a question I wrestle with.
"The Ali before the three-and-a-half years out was absolutely superb. Nobody could touch him, he was so fast.
"Ali was 6ft 3ins and the guys he fought were about the same size. How would he do against a 6ft 9in-guy who is an incredible boxer with great footwork?
"I grew up with basketball in New York and the center was barely 6ft 6ins. A guard was 5ft 10ins. Now LeBron James is as quick as any guard but he's 6ft 10in. Imagine LeBron playing against the small guys of my era. It would be a joke, he would score 60 points every game.
"I can't see Ali competing with a 6ft 9in-guy like Fury. We had big guys in the old days but they were slow, lumbering. They were jokes who couldn't fight, they were just big. It's all changing. Look at Fury, Anthony Joshua, Deontay Wilder. They are huge guys.
"But maybe if Ali was in this era he would be 6ft 6ins instead of 6ft 3ins because of the nutrition. Everything has changed."