Let the catfights begin!

During the season premiere of American Idol Season 12, Nicki Minaj and fellow judge Mariah Carey wasted no time showing each other who's boss.

At one point, Mimi begins to brag that her holiday hit "All I Want for Christmas" is still number one after 17 years. Nicki's response at the 2:18 mark ... "She's a b**ch, she's a b**ch ..."

Hopefully Keith Urban and Randy Jackson will be able to keep the judging panel under control. Meow!

Mariah watched the premiere from her bed while snuggling with daughter Monroe. Adorbs!