Heavyweight champ Deontay Wilder says you're only as good as your last fight ... and that's why Floyd Mayweather could ruin his ENTIRE LEGACY if he gets blasted in his upcoming fight.
Floyd is putting his 50-0 record on the line when he faces off against undefeated 20-year-old kickboxer Tenshin Nasukawa in Toyko on New Year's Eve in what could be an MMA rules fight (they're still working it out).
Wilder says Mayweather is putting more than his perfect record on the line because if he looks bad, his entire untouchable career could be tainted forever.