And the next episode of the series - which airs on 5* in the UK - sees their sniping step up a notch as Nicki walks out from the panel following a spat with her female rival, as well as fellow judge Randy Jackson.
Following hopeful Summer Cunningham's audition, the panel start rowing about country music as the contestant offends Keith Urban by saying she'd 'done the country thing'.
Mariah kicked things off by saying: "When you said you 'did the country thing' you annoyed Keith!"
At this point, Nicki chimed to say: "Why are we picking her apart because of a country comment? You guys make comments about everybody in popular music all day."
Flicking her hair and doing her best don't-mess-with-me-face, Mariah replied: "Oh really, is that what I do? I’m trying to help her as opposed to just talking about her outfit".
Randy then got involved to add: "I’m just trying to help you, a little bit... 30 years... Insight."
Nicki was having none of it though and flipped before pushing her chair away the desk and ranting: "Oh, you’re right. I’m sorry I can’t help her. Maybe I should just get off the f****ing panel. Let me get off the panel. Finish the show. I’m done."
Sat there smirking (and flicking her hair, obv), Mariah joked: "That was my move. I was gonna do that the next time she bagged on me."
Nicki could then audibly be heard yelling 'shut the f*** up!' as she marched behind-the-scenes.
Wowzers. And here was us thinking that it was Mariah who was going to be the biggest diva...
Name: Randy Jackson Seasons: 1-12 Known for: Coining the phrases "Yo dawg" and "It's a little pitchy."
Name:Paula Abdul Seasons: 1-8 Known for: Crying while judging.
Name: Simon Cowell Seasons: 1-9 Known for: His brutal judging tactics.
Name: Kara DioGuardi Seasons: 8-9 Known for: Introducing the world to "neckitude."
Name: Ellen DeGeneres Season: 9 Known for: Walking away from her five-year contract after only one season.
Name: Jennifer Lopez Seasons: 10-11 Known for: Stealing the spotlight from the contestants.
Name: Steven Tyler Seasons: 10-11 Known for: Criticizing and hitting on contestants with confidence.
Name: Nicki Minaj Seasons: 12-? Trademark: Feuding with Mariah Carey whenever possible.
Name: Keith Urban Seasons: 12-? Known for: Making country references whenever possible.
Name: Mariah Carey Seasons: 12-? Known for: Trying to compete with Nicki Minaj's diva lifestyle.