Nicki Minaj blew up at Mariah Carey, threatening to knock her out during the American Idol auditions in Charlotte, North Carolina on Tuesday. Sources told TMZ Nicki swore at Mariah and threatened, “I’m gonna knock you out!” The gossip site obtained footage in which Minaj goes on a non-stop rant, shouting the entire time. Mariah seems to be responding, but is inaudible on the tape, while fellow judge Keith Urban sits between them, trying at times to calm Minaj down and throwing up his hands in defeat when she refuses to stop shouting. Although her threat to Mariah was made before the video starts, Minaj is heard furiously saying : “I told them I’m not f*ckin’ putting up with her f**kin’ highness over there.” The incident apparently occurred after a disagreement about a contestant’s performance. Although it’s unclear what Nicki was upset about, a few weeks ago during auditions in NYC, Mariah constantly interrupted her when she was critiquing a contestant. TMZ also reported earlier that when producers called Mariah to tell her that Nicki had been chosen to join her as a judge on the show, she hung up on them. Producers are reportedly very concerned about what’s happening and ended the auditions for the day so everyone could cool down.