Diddy is facing a new rape allegation, one that dates back to before he was famous ... and the alleged victim says it went down during an already infamous NYC event.
The accuser, who's filing as a Jane Doe, says she was attending a December 1991 charity basketball event at the City College of New York, which was co-sponsored by a then up-and-coming producer, Sean "Puffy" Combs.
She and a friend were invited by an unnamed rapper set to appear at the event, she claims in the lawsuit -- when she and her friend arrived, she says the crowd outside was large and getting unruly, and she convinced a security guard to let her and the friend in early.