The lawsuit, obtained by TMZ Sports, was filed by Blake Adams in L.A. county earlier this month.

In the docs, Adams claims he was dining at Delilah in West Hollywood on Dec. 9 -- when he noticed McGinest, a famous USC alum, walking past his table.

Adams says in the suit he asked the Trojans legend about SC's most recent game -- a loss in the Pac-12 Championship to Utah -- when McGinest bristled.

"Why the f*** are you talking to me?!" Adams alleges McGinest told him.

According to the suit, McGinest walked away ... but then "suddenly reappeared" moments later, and approached Adams.

"McGinest leaned down," the suit states, "and stated in [Adams'] ear, 'Now what did you say bitch ass n****."

Adams claims he was startled and afraid ... and told the former NFL star "he was just a fan trying to say hello."

"McGinest suddenly, unprovoked and without reason punched [Adams] in the face," the suit states.

Adams claims several other men jumped in to assist in the attack -- punching him repeatedly. At one point, he says Mcginest grabbed a glass bottle and struck him in the head multiple times.

He said he suffered serious and permanent injuries in the melee.

Adams is suing McGinest for unspecified damages. He's also suing Delilah, claiming the lounge is known as a "playground for celebrities and professional athletes to do whatever they want with no consequence or repercussion."

McGinest, a New England Patriots Hall of Famer, was arrested and has been charged with two felonies over the incident. He issued a statement shortly after it happened, saying he was sorry for his actions.

"To my family, community, friends, and youth I mentor," McGinest said in an apology statement, "please know I feel horrible for my actions and take full responsibility."