Kelly, who will return to US screens tonight (11 September) as a judge alongside Simon, Demi Lovato and Paulina Rubio, said the music mogul won't be able to handle the pressure of three fiesty females!
Speaking to Ryan Seacrest on his radio show, On Air, she said: "Simon is probably thinking, 'what was I thinking getting three big doses of estrogen on the panel with me' because we bite.
"If Simon picks on one of us, he's taking on all of us, so we're all ready to gang up on him."
We reckon Kelly will be true to her word, as the female judges have struck up quite a bond since filming together and are now fully fledged BFFs.
Even last month, the ladies gushed about their friendships while attending a FOX party in Los Angeles, and Demi has also spoken about the new judging dynamics.
She told MTV News in July that the line-up brings a "lighter energy to the show. Instead of having feuds on the panel, it's all positive."
With the three ladies and Simon Cowell in tow, we're expecting a few fireworks and plenty of girl power!
The X Factor USA airs in the US on 11 September on FOX. It is expected to air on ITV2 in the UK at a later date.
Watch a video of Simon's relationship with his fellow female judges below: