How would Ali have fared against other heavyweight greats?

Muhammad Ali is widely considered to have reached the peak of his powers when he defeated Cleveland Williams in 1966. AP Photo

Muhammad Ali might have been the greatest heavyweight of them all, but that doesn't necessarily mean he would have beaten every other heavyweight champion.

It's true that styles make fights, as Ken Norton -- who is not considered a great heavyweight -- showed in his three tough, close fights with Ali.

Size comes into play, as well. Some of the modern heavyweights would have been much bigger than Ali.

Ali's greatest assets, of course, were speed, reflexes and mental and physical toughness. His former physician, Dr. Ferdie Pacheco, once remarked to me: "Ali showed you can be tough without a face that looks like it's been through a meat grinder."

Ali also had a quality that the great ones possess in that he could find a way to win. Could he have found a way to beat everyone, though? Let's look at mythical matchups between Ali and five heavyweight champions.

For the purposes of this exercise, we will take as our model the Ali who destroyed Cleveland "Big Cat" Williams in three rounds in what is generally considered the most dramatic demonstration of his punishing artistry.

Ali vs. Jack Dempsey

The size disparity would have been pronounced in this contest. Dempsey was really just a cruiserweight by today's standards, at around 192 pounds, which means he would have been giving away some 20 pounds to the Ali of the Cleveland Williams fight.

True, Dempsey annihilated Jess Willard and Fred Fulton, both 6-foot-6, but these old-time fighters had nowhere near Ali's speed and fluid boxing skills -- there was simply no comparison. Dempsey had problems with the smart-boxing Tommy Gibbons and, admittedly late in his career, was twice basically outclassed by the scientific Gene Tunney, the long count of the rematch notwithstanding.

Verdict: Ali vs. Dempsey would have been a mismatch, with the old Manassa Mauler being confused, outsmarted, outboxed and outclassed.

Ali vs. Joe Louis

I consider Louis the greatest of all heavyweight champions in terms of physical tools. He was a superb fighting machine. At about 6-foot-2 and 200 pounds, he would have been the smaller man in the ring, but he would also have been the puncher in the fight. Louis might have been able to put heavy pressure on Ali -- moving in behind the jab, getting off with sharp, hard hooks and right hands, especially if Ali went to the ropes. One must think back to Louis' first fight with the smaller Billy Conn, though, when he was clearly outboxed for 12 rounds before winning in the 13th. Ali would have been able to avoid sustained punishment by moving this way and that, and his snaking left jab and crisp rights, backed up by some well-judged combinations, would have scored points.

Verdict: Ali by decision in a grueling fight.

Ali vs. Rocky Marciano

Marciano won the famous computer fight against Ali, but the real thing would have been very different.

No one doubts Marciano's durability, heart, fantastic conditioning and heavy hitting. He would keep coming, and he was almost impossible to discourage, but the Brockton Blockbuster would have been a cruiserweight today, under 6 feet and weighing less than 190 pounds. Ali would have towered over him.

I think Ali would just have been too big, too fast and too skilled for Marciano, who usually needed to win by attrition, boring forward and breaking down the clever boxing types. Marciano would not have had the chance to inflict the damage necessary to slow down Ali, and it's easy to visualize the Rock having to take a lot of punches and perhaps suffering cuts. (True, the aggressive, shorter Joe Frazier beat Ali in 1971, but Frazier applied a faster type of pressure than Marciano, while Smokin' Joe was also a bigger man physically, about 15 pounds heavier than Rocky.)

Verdict: Ali by decision or late stoppage.

Ali vs. Mike Tyson

This would have been a fascinating fight. Tyson -- the 21-year-old version -- had the Joe Frazier type of attacking speed, and Tyson's punches were fast when he was at his best. Although he would have been giving up five inches in height to Ali, he was more powerful physically, and at about 218 pounds he would have been a bit heavier.

For the first four, five or six rounds, Tyson would have given Ali a desperate struggle. He would have been going at him hard, and Ali could not have avoided all the shots. Tyson's left hook might well have put Ali down -- certainly Ali would have been rocked and staggered. Ali's many admirers would have been very, very worried.

Eventually, though, Ali's cool boxing brain and his character would have pulled him through. He might have been obliged to hang on to get through some rough moments, but Ali's superior will and greater mental stamina would come into play. He would probably talk to Tyson: "Boy, you're getting tired now -- you're in trouble."

There is a good chance that Tyson would have started to unravel as Ali came back at him with jabs, right hands and combinations, in effect bullying the bully. In the later rounds, Tyson would have been wishing he were somewhere else, while the crowd would have been joyously chanting: "Ali, Ali, Ali."

Verdict: Ali by decision or late stoppage.

Ali vs. Lennox Lewis

Size, styles and psychology would all have played a big part in this fight.

Lewis, while not nearly as fluid or as fast as Ali, was a very big heavyweight at 6-foot-5 and around 245 pounds. Ali would have been the small man in the fight.

Ali's taunting of an opponent, the undermining of the other man's confidence, might not have worked against Lewis, who had a sort of professional remoteness.

Ali would have needed all his skill, moving Lewis around, seeking to get off first with the jab, darting in to score and sliding out, scoring in bursts. He did this and made it look easy against 6-foot-6 Ernie Terrell, but Lewis was a much bigger-framed, technically superior fighter and clearly a bigger puncher than the long and lanky Terrell.

Lewis' long-reaching left jab could have given Ali problems, and his right hand would have been a threat throughout the bout. Lewis, steady and calculating, would have been confident in his size and power and wouldn't have been intimidated. He could have timed his left hand, enabling him to match jabs with Ali. Lewis might even have outjabbed him, as Ken Norton was able to do.

Ali would have had to take some solid right hands, and his fake wobble wouldn't have rattled Lewis, who would simply have waited for an opportune moment to unload another thudding shot.

It's doubtful that Lewis would have lunged off-balance in his attempts to land the right; he would have held the center of the ring and waited for Ali to take risks.

In terms of style, and always bearing in mind the size difference, I think that the much bigger Lewis might have been completely wrong for Ali.

Verdict: Lewis on points in a tactical match without many thrills.

Graham Houston is the American editor of Boxing Monthly.