UFC legend Chuck Liddell says there ain't a chance Floyd Mayweather steps inside the Octagon -- 'cause any MMA fighter would beat the living hell outta him!!
"C'mon man -- he can't fight in the UFC," Chuck told TMZ Sports.
"Why would he do that? He's just gonna get hurt."
The Iceman, who was out visiting a children's hospital, clearly thinks Floyd wouldn't stand a chance in an all-out scrap ... and told us it'd be over quick if he rematched Conor McGregor.
FYI, Mayweather basically said he ain't crossing over (for now) ... but if he does, can't say he hasn't been warned.