Simon Cowell and Louis Walsh ganged up on the Girls Aloud beauty, slating her band and her solo performances.
The spat began when a raunchy girl group, called Madame Butterfly, came on stage at London’s ExCel centre during Wednesday’s trials.
Simon sniped to them that they must not take inspiration from British groups, like Girls Aloud. And he asked the foursome who they were influenced by, saying: “I bet you only like American groups, like Destiny’s Child.”
Stony-faced Cheryl stayed quiet. One of the singers eventually said they liked Girls Aloud too.
Then to add to the frosty atmosphere, Louis took his own swipe at the 26-year-old when a Romanian male model performed her single Fight For This Love from her 3 Words solo album.
Beefy Adrian had the audience in hysterics as he pranced around the stage warbling an out-of-tune, cringe-worthy version of her hit.
Afterwards, Cheryl laughed that he had made a “great song choice”.
But Louis wiped the smile off her face, quipping: “That was about as good as you can do it live.”
Cheryl didn’t retaliate but looked furious as he and Simon sniggered.
An insider said: “Their nasty comments really hit a nerve with her.
“She’s never been fully confident about her singing ability, especially since launching her solo career and not having the other girls on stage.
“To be humiliated in front of thousands of people by Simon and Louis was really a step too far.”
Cheryl was criticised during last year’s X Factor when she performed Fight For This Love, but pre-recorded the vocals instead of singing live.
Louis’s attack looked like retaliation as he and Cheryl had earlier traded insults about their teeth.
Show supremo Simon had told Louis to have his gnashers whitened after the last series.
But Cheryl, who has had hers fixed with porcelain veneers, claimed they still looked grubby.
He shot back: “At least I’ve got my own teeth still.”
A source said: “Cheryl was a bit taken aback. It got a bit catty.”
We revealed yesterday how Cheryl is set to revert to her maiden name after Simon called her Tweedy at Monday’s auditions.