Ex-NFL wide receiver Titus Young ducked out of a court-ordered treatment center and beat a guy so badly, the dude was hospitalized with brutal injuries ... this according to a lawsuit obtained by TMZ Sports.
We broke the story, the former Detroit Lions star was arrested for allegedly attacking a guy in L.A. on January 30th. Now, the alleged victim has fired back with a suit, blaming Young's parents for not turning their son into cops before the incident.
FYI, Young was ordered to spend 12 months in a treatment facility after pleading no contest to felony battery back in May for a separate incident.
But according to the suit, Young left and went to his parents home -- a violation of the terms of his deal.
"The Youngs knew both that Titus Young was in violation of the terms of his probation and that he had extremely violent tendencies fueled by a history of illegal drug use," the accuser states in the suit.
The man claims while staying at the home, Young "ambushed" his neighbor with a "hard object" and busted the guy wide open -- causing "deep wounds to his head and eyes."
He also says he may suffer blindness as a result of the attack.
He's suing Titus and Young's parents for unspecified damages.