Yeah, and Ali destroyed him of course.

Whatever, look, I and many others beside find it ominous to say the least that Marciano retired just as a slick, crafty heavyweight with the perfect style to beat him started making waves (Patterson).

Whether Rocky wouldv'e beat him - who can say? But I think he sensed an imminent changing of the guard, and bowed out. Fair enough. He was a great champion and I'll never say otherwise.