Joe Louis '41 vs. George Foreman '73

It would probably last a bit longer, but Frazier had wrong style to beat Foreman. He had to fight on the inside, but Foreman was too big and too strong for that with his pushing techniques.

Louis wouldn't have the same problem though.

 

Louis would beat him. As skilled as Frazier was, he had a one dimensional style, he always went forward, and against the far bigger and stronger George, who had the appropriate style for Frazier to boot, that was suicidal. Joe Louis on the other hand could fight well in any range and was not that much smaller than Foreman. George does obviously have the power to beat Louis, but he lacks everything else to actually make the Knockout possible.

That rear hand that was used to push and parry his opponent's jab ? Gone out of the window, because George carried it so forward that he was open to a left hook. Hell, the left hook is literally the first punch that Ali landed in the rumble in the Jungle because of this exact scenario, and Louis had a far better left hook that was just as fast as Ali's, only far more vicious and powerful. Foreman's long guard also left him wide most of the time, and being open is the very worst thing you can do against arguably the best puncher of all time .

Every time Foreman punched, his shots while powerful were very wide and crude, and he definitely was not a fast puncher to compensate for that. Louis had the defensive capabilities, the handspeed, the power and the killer instict to make him miss and pay dearly. Resulting in a Knockout somewhere in the middle rounds.