Undefeated heavyweight prospect Deontay Wilder beat up out of a real life Internet troll who had been harassing him for years .
TMZ Sports caught all the action on video.
The guy who got his face bashed in is Charlie Zelenoff -- a wannabe fighter who’s been trolling Wilder for years with harassing phone calls and deeply personal jabs on social media.
The TMZ website reports Wilder claims Zelenoff has not only hurled racial slurs at him -- but also made disparaging comments about his young daughter, who was diagnosed with spina bifida.
Zelenoff had recently challenged Wilder to fight him at a boxing gym in L.A. -- and Wilder, deciding enough was enough, met him at the Hollywood Boxing Gym late on Wednesday night.
Wilder tried to fight Zelenoff in the ring -- but Zelenoff threw a cheap shot and ran for the door
When he finally returned, the squared off on the main floor of the gym –he got himself a beating.
When Zelenoff picked himself up off the floor ... a furious Wilder told him, "Don’t you ever call me a n**ger again. Don’t you ever say you’re going to tape my daughter."
Zelenoff eventually ran from the building ... again ... but not before saying, "I’m the best. I’m still the best."
Click on the link below to see the troll get a pasting.