Yesterday American Idol bosses were forced to cancel filming after Nicki Minaj threatened to 'knock out' Mariah.
TMZ are currently running a video of the incident in which Nicki can be heard yelling at her fellow judge.
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In the video Nicki can be heard saying: "I told them I'm not f*****g putting up with her f*****g highness over there. Figure it the f*** out. Figure it out."
According to a source on set, Nicki also told Mariah: "I'm going to knock you out."
Nicki's major diva strop was however reportedly provoked by Mariah Carey's relentless snide remarks about the rapper.
A source told Mouthtoears.com: "Nicki Minaj walked off of set because Mariah Carey kept making jabs at her."
"Nicki's manager and team convinced her to come back to the show. Mariah kept at it and called Nicki 'a b****' and then proceeded to cuss her out. Producers had to stop filming and call it a night."
And we thought the tense atmosphere between Dannii Minogue and Sharon Osbourne was awkward.
Nicki Minaj previously denied rift rumours between the two telling Access Hollywood: "Mariah's a legend and I just want to say that… I'm sitting next to a woman who I've looked up to since I can remember enjoying music."