Probably Norton 3. Even though I suspect more than 50% of pundits and fans score that to Norton, it was still a close fight against an excellent fighter who was a stylistic nightmare for Ali. Ali was never the same again post Frazier 3 as the already past prime version he was in that fight. Pickings for excellent Ali performances post Manilla are slim to non existent.
Even though the opponent was one of Muhammad's low grade ones,I'd say the Richard Dunn fight. His last fight before the Antonio Inoki debacle. I've always believed the kicking Muhammad allowed himself to take in his legs accelerated his decline which was clearly building monentum post-Manila.
Richard Dunn, zero question. Just six weeks after going a dismal Championship Distance at a career high 230 pounds for Young (nonetheless initiating for 15 rounds as he did in Bugner II), he'd trimmed down to 220 and looked as if Manila had taken nothing away from him. He could've taken out the tall but chinny spirited British southpaw any time he wanted (as a highly aroused Bugner did to Dunn next), but kept to his fifth round prefight prediction, written on the inside of his gloves. Ali had figured out how to deal with the second southpaw to ever challenge for the HW Championship. He wasn't uncertain and working unnecessarily hard as he did at his peak for Mildenberger, but went directly to his darting right lead in round three. We need to forget about Dunn the way we need to forget about Cleveland Williams, and focus carefully on what Ali does. This is his final bout before Inoki takes away his knockout ability by eliminating his ability to plant his powerful legs for driving force. I've no doubt Ali in Munich was good enough to do what he did to Foreman and Frazier in Manila. He could still be superb at 34. If he hadn't gone to Tokyo to have his legs repeatedly kicked at almost to the point one had to be amputated, he might've generated six successful defenses in 1976, won conclusive victories in rematches with Young and Foreman, the verdict in Norton III would not have been controversial, Evangelista, Shavers and Leon do not go the distance, Earnie does not inflict terminal brain damage, he might become the first HW Champion to get to 30 defenses, and if he doesn't retire first, Norton never claims a title and Holmes has to be the one to eventually dethrone him, and over the distance. Following Young, he's never in less than top condition again. As it was, Norton III, Shavers and Leon II were obviously more historic, but Dunn is by far the superior performance, the last time he really shows off his legs (to begin the match). I do not think it's charity or hyperbole that Ali said the highly spirited and aggressive Dunn would've dethroned him if he was in the same kind of shape he was for Young. Dunn had decisioned Bunny Johnson over the Championship Distance, avenging a knockout loss to win the rubber match in their rivalry, reversed a career opening knockout to McAlinden, had actually beaten some decent punchers like Neville Meade, and in his career finale, he even took Knoetze into round five. Muhammad's shape for Young was so poor that's it's obvious his lackadaisical power in that one wouldn't have been sufficient to hurt even the china chinned Dunn. (What Bugner did to Dunn and Denis raises serious questions about what he might've achieved if he'd gone into every bout with bad intentions. He should've crushed Bodell like Jerry Quarry did, and Henry Cooper didn't have nearly the chin to take his hardest fire. Cooper went very controversially to Bugner, but that one had no business getting anywhere near the final round.) In chronological order, the GOAT's best performances after Zora Folley were Jerry Quarry II, Foreman, Manila and Dunn. (Yes, the FOTC was the FOTC, but I think Frazier's absolute peak consisted of the JQ I/Ziggy/Ellis I troika prior to Joe fracturing his ankle, and Ali rushed into it ahead of an anticipated negative Supreme Court ruling, so not at his post exile best potential.)
