Evander Holyfield says Tenshin Nasukawa is in deep trouble -- because Floyd Mayweather is gonna "beat the daylights" out of the Japanese fighter when they box on New Year's Eve.
The Real Deal touched down Thursday night in Los Angeles -- where he'll be attending the big Deontay Wilder vs. Tyson Fury heavyweight title fight on Saturday at Staples Center.
Holyfield -- one of the greatest heavyweights of all time -- says he thinks Deontay could put Fury to sleep with that deadly right hand ... and he's excited for what could be one of the most action-packed events of the year.
As for Mayweather, Evander acknowledges that Tenshin's age -- he's only 20 years old -- could give him an edge during the 3-round exhibition fight ... but when it comes to doing it, Floyd's gonna put a hurtin' on him.
"You playing [Floyd's] game, so he's supposed to win," Evander told us ... "He's not gonna fight anybody that can beat him!"
Tenshin released a sparring video earlier this week showcasing his speed -- and while it's impressive to us ... Holyfield thinks it'll be child's play for Floyd.