NBA superstar Tony Parker -- who was injured when Drake and Chris Brown's posses squared off -- is suing the NYC nightclub for $20 million, claiming it should never have let Rihanna's exes in at the same time ... and Chris Brown as well as Drake could end up as defendants.
The San Antonio Spurs star filed the lawsuit Thursday in NY State Supreme Court ... against W.i.P. Nightclub -- and in the suit he alleges the club's security was negligent for allowing the brawl to ever happen.
The lawsuit alleges club management, knowing there was "bad blood between Drake and Brown," was driven by the almighty buck and continued selling alcohol to the participants in the brawl, despite the fact that some were "visibly intoxicated."
Parker's injury is a huge deal because it could affect his NBA career, and -- more immediately -- his performance in the Olympics with the French national basketball team.
As for why he would sue for $20 MILLION? Parker is in the middle of a $50 million contract with the Spurs.
As for whether Chris Brown or Drake will be added as defendants, Parker's lawyer, David Jaroslawicz, tells TMZ ... he's waiting for the results of the police investigation. He also wants to review the surveillance tape before making his decision.