Rapper and Roc-A-Fella Records co-founder Jay-Z [ tickets ] was freed on $50,000 bail following the stabbing of Untertainment Records head Lance "Un" Rivera at a CD release party in New York last week. He is due in court on Jan. 31 to answer to first- and second-degree assault charges, among others.

According to a report in Newsweek, the incident took place at a club near Times Square during a celebration for rapper Q-tip's solo debut. "Jay-Z approached [Rivera], they had a few words, they became loud, and then this big commotion began," an unidentified female rapper told the magazine. "One guy I couldn't see hit Un with a bottle and then Jay-Z pushed something in his back and in his stomach, and Un began to sort of bend over and people started yelling."

Rivera was treated for stab wounds at a nearby hospital and released. Jay-Z denied involvement in the incident in a prepared statement issued by Island/Def Jam, which distributes Roc-A-Fella Records.

Jay-Z and Rivera may have had a falling-out following the premature distribution of Jay-Z's forthcoming album to New York radio stations, for which Jay-Z's camp reportedly holds Rivera responsible, according to Newsweek.

Jay-Z, whose real name is Shawn Carter, reportedly appeared at Q-tip's album release party after attending his own record release shindig at Irving Plaza. Rivera--whose label's top artist is Lil' Kim--reportedly wasn't invited to Jay-Z's event, despite the fact that he shares a co-production credit on a track on Jay-Z's forthcoming album, "Vol. 3 ... Life and Times of S. Carter."

Rivera hasn't commented on the incident.