I think these people are nuts to think Marciano beats Tyson at all . Marciano fought Guys who were barely cruiserweights to today's standards and was knocked down by guys that probably hit no where as hard as Tyson and not to mention guys like Foreman, Shavers . I agree Marciano was able to take a considerable amount of punishment , especially against Ezzard Charles when his nose was almost split in half and his eye almost closed by Walcott and behind on points and he came through when he needed to with the amazing punching he had and was a constant pressure fighter like Tyson, but hard to imagine knocking out Tyson when Tyson appeared to be much faster with better skills ,and with the exception of foreman, Shavers, should be regarded as the hardest hitting heavyweight . I see a young Tyson scoring easily with knockdowns and opening cuts on Marciano and have to go with a early ko or possibly mid/ late round stoppage .

  I have not seen anyone, after all this time, who could beat Rocky Marciano ( Except maybe Ali or an airplane). 

Marciano was a great, great champion, but he was giving up way too much size. This would have been heavyweight against a cruiserweight. The heavyweight sizes of today would have been too much for Rocky.

The Brockton Blockbuster vs Iron Mike. Tyson is always dangerous but Marcino could get inside and club the daylights out of him. This would be the fight of the century but it would not last very long. Marciano trained like a fiend. He never backed up.He took Jersey Joe Walcotts' best shot and got up off the floor to hit him with that famous right to the jaw. Tyson was a coward when someone started hitting him back. I think the Rock would knock Tyson out in the second round with a right uppercut, left hook, and a smashing right cross. And hopefully leave the ring with both ears intact.

Awesome fight but Tyson at his best would have overwhelmed the 40 lb lighter Marciano. KO in the mid rounds. Lets not forget when tyson was young he was a great skilled tactician with blinding speed and ko power in both hands.

Be a hell of a fight. Tyson has the weight and the reach, but Marciano has the heart and the guts. I'd give this to Marciano by a decision at least, and quite likely a knockout after Tyson starts to feel the pain.

Rocky Marciano had way too much heart for Mike Tyson, who had very little. Mike would've crumbled the way he did every time somebody actually fought back. Don't believe me, look at his record, it speaks for itself.

It is really hard to predict what would have happened here, but two things are for certain: (1) it would have been a brutal display of power; and (2) there would have been an epic knockout. On one corner is the 'Brockton Blockbuster', Rocky Marciano, whose punch was once measured to be the equivalent to an armor-piercing shell. On the other corner is the infamous 'Iron' Mike Tyson who was arguably the most feared puncher in heavyweight history. In looking at this dream match-up, a lack of defense is not entirely beyond any realm of possibility as both would have come out swinging. Marciano would have to be able to wear out the storm of Tyson to knock him out in later rounds. But if Tyson can land brutal shots early, Marciano may be in trouble. The factor then would be heart, and if this is measured, I see Marciano prevailing in the bitter end.

There is no point in looking back on old fighters and thinking they are better than more recent ones because people look back with rose-coloured glasses. Half of these guys had a beer+burger diet, have you ever seen that many well toned muscular fighters from the olden days. Put it this way Marciano STARTED boxing at 21-Mike Tyson who was fighting arguably in a greater era of boxing was already world champion by that age. If people tok about marciano wouldnt b scared of tyson-thats probably because he had the MAFIA behind his back,if he didnt then he would probably be just as intimidated as any other boxer,not because hes not a good boxer but because its human nature to be intimidated by Tyson!I also think that Tysons punching power and hand speed would be just to great for Marciano and if people tok about the damage Marciano gave his opponents then obviously they arent thinking about the difference in SIZE and WEIGHT of gloves that they both wore!!

Tyson is a bitch who never won a fight against anyone who stood up to him. Make Tyson think beyond round 3 and he will panic/run scared/piss his pants/eat your ear/lose the fight. Marciano would not be scared of Tyson's bulls#$% disturbed black man image and knock him out during the middle rounds. Everyone talks about Tyson's punch- check out the brain damage Marciano gave his victims.

Hard to say because when you combine 2 knockout artists it can be unpredictable. I agree that Tyson has some size advantage and it is possible he could get Marciano in the early rounds, but Marciano was known for weathering storms and coming back to knockout his victoms. In this fight if Marciano gets past 5 rounds he wins. Tyson gets discouraged and runs out of gas after this point.

The greatest fight in history. Marciano will most likely win by late round knock out