Floyd Mayweather has laughed off Logan Paul's significant size advantage, but the social media star has warned that he is ready for a 'physical' fight.
Mayweather and Logan Paul will share a ring on Sunday night from midnight, live on Sky Sports Box Office.
The YouTuber-turned-boxer has claimed that he must weigh-in at 190lbs (equivalent to a light-heavyweight) at Saturday's weigh-in, while Mayweather must be 160lbs (equivalent to a middleweight).
Mayweather never boxed above 154lbs as a professional - he was a world champion in five weight classes.
Logan Paul also claimed that he would incur a $100,000 fine for every pound of weight if he exceeds his limit.
Asked about being dramatically lighter than his rival, Mayweather told Sky Sports: "I don't worry about that. I'm a fighter, this is what I do.
"I was a professional for 25 years, I have seen every style, and always come out on top.
"Most of the time when I fight these guys, I am giving away 20lbs. When I fought at 140lbs, the guys would go up to 160lbs [after the weigh-in]. When I fought at 147lbs, the guys went up to 167lbs.
"So I don't worry about weight, height."
But Logan Paul insists Mayweather has made a mistake, telling Sky Sports: "Of course, why do you think there's weight classes in boxing?"
The former college wrestler and his trainer Milton Lacroix believe the extra pounds of muscle will pose problems to Mayweather.
"For Floyd's sake, let's hope it doesn't get physical," Logan Paul told Sky Sports.
"Yeah for sure [it could get ugly]. It's a fight and the rules are, I don't know, kind of moronic. Anything could happen."
Speaking to Showtime Sports, Lacroix added: "If Floyd decides to start chasing Logan, and we grab him.
"Remember, we've got a wrestler going against a boxer. Sometimes wrestlers when they grab you, they know how to lock, they know how to hold you. They know how to twist and turn you. Anything is possible."
Knockouts are permitted in the exhibition bout, and the glove size has been lowered to 10oz, but there will be no judges.
"There's a difference between YouTube boxing and elite boxing and elite fighters," Mayweather told Sky Sports. "You guys will see the difference.
"At first, they were talking about 14oz gloves, 16oz gloves.
"From the beginning, I wanted 8oz gloves for me as well as Logan Paul.
"Hopefully it can change to 8oz."
Logan Paul said about the lighter gloves: "Good, that's how I want it."