power = Marciano

speed = Johnson

Skill = Johnson

Chin = tie

I take Johnson by UD.

He would clinch Rocky, and Rocky wouldn't like that. He'd clinch him and man-handle him, he did that to smaller, aggressive fighters. Rocky was about 188lbs and Johnson 10lbs heavier and 2'' taller (he was 6''1, Rocky was 5''11) and Johnson's reach was about 74 inch while Rocky had a 67 inch reach.

Rocky was relentless but against someone like Johnson, he'd just keep Rocky on the outside and clinch him whenever he tries to come inside (he did this a-lot). He had slightly better footwork (Johnson's footwork was good for his time, but compared to the fighters of the 1950's, it wasn't much better). Johnson had faster, and more accurate hands - he had natural strength and would counter Marciano, cut him up, toy with him, etc.

Marciano would land but Johnson would land the more accurate punches, and probably knock Rocky down.

Johnson by lopsided UD.

@Ken, I don't think ALI really ranked Marciano ahead of Frazier. He respected Marciano and didn't want to talk ill of him, but ALI has gone on to state that Frazier would beat Marciano. Frazier gave ALI so many problems in their third bout, he (Frazier) was essentially a bigger version of Marciano.

In a 15 round fight it could go either way.

Jack Johnson was an intelligent but not so big a boxer similar to Walcott [but probably a bit more technical, sadly his film quality sucks]. Ezzard Charles did pretty good and IMO won the first fight with Rocky but Charles had more power than J. Johnson and that's a big difference. Rockys speed and boxing skill is also underatted, he could out box an old Louis. Rocky tended to box with his opponents at first, then he would get into his groove [like any great swarmer] and throw a bunch of punches, in his case haymakers.

Many men could hold Rocky down but if you didn't have exceptional power to keep him away early [like Ezzard Charles], you were doomed.

Johnson didn't have much power but this fight would go the distance, both were 20 round fighters. Johnson once went over 30 rounds against a 6'6.5'' boxer which is incredible considering his lack of power.

Johnson I think was the best prototype modern heavyweight boxer (in tie with Joe Louis) while Marciano was I think the best modern heavyweight brawler/swarmer with the highest work rate, endurance and durability. So this would be a perfect clash of basic boxing fighting styles. I think it will go the way of the Ali-Frazier series that we actually saw in the 70s, the only difference is that I think Marciano would get the better of Johnson if they fought three times prime for prime.

In speaking of old-time boxers, Ali ranked Marciano #1 and was not sure if he could beat him, He also ranked Marciano ahead of Frazier.