According to one site, Nicki went head to head with the diva during an audition in Charlotte, N.C., shouting out: "If you've got a f–king problem, handle it!"
Later, the hip-hop star allegedly threated to "knock [Mariah] out."
An insider told E! News, "This is the sort of thing producers considered might happen when they cast Nikki opposite Mariah, but not this bad and not this fast."
The source added, "They have to protect Mariah to make sure she doesn't walk. After everything it took to get that panel in place, they need everyone, especially Mariah. She was their first choice."
So, how will this season play out? Threats aren't taken lightly, and the source added, "Physical threats are taken seriously and [show producers and Fox execs] are still deciding how to handle it. It's not an easy call."
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