Nicki Minaj started swearing at Mariah Carey during "American Idol" auditions in Charlotte, North Carolina.
The rapper also threatened Mariah, saying, "I'm gonna knock you out."
The video of the incident shows an angry Nicki shouting, "I told them, I'm not f*$%in' putting up with her f*$%in' highness over there."
Sources say that she later threatened to "knock out" Mariah, but that part wasn't captured on tape.
It all went down over a disagreement about a contestant's performance.
After the blow-up, producers ended the auditions for the day so the two judges could cool down.
The show's producers are now worried about if the ladies will be able to get along for the rest of the season.