Show boss Simon, 54, was feeling poorly so he took the afternoon off, leaving 31-year-old Cheryl to show him just what she can do.
READ: CHERYL FERNANDEZ-VERSINI WANTED TO KEEP WEDDING A SECRET: "UNFORTUNATELY IT WAS LEAKED"
According to audience members the singer tried the tough-talking Simon is famous for, but it didn’t go down too well.
Especially when she told one hopeful that he needed to be more like Justin Bieber…
VIDEO: CHERYL FERNANDEZ-VERSINI TWERKS UPSIDE DOWN AGAINST A WALL
Cheryl was critiquing a crazy singer called Sammy when the audience backlash occurred.
She told him: “I think Simon was right, you could be your own five-piece band, but I think you should do stand up or something. I just wouldn’t know how to mentor you.”
Sammy replied: “But I don’t always have to be mental.”
READ: X FACTOR VOICE OVER MAN TOLD TO START PRACTICING CHERYL'S NEW SURNAME
The former Girls Aloud singer wasn’t having it though, and hit back: “But every time we’ve met you, you are.”
One person from the audience told the Daily Star: “Cheryl thought she was being tough but it didn’t go down well.
“The moment she mentioned Bieber, the entire audience started booing her and shouting stuff. It was really intense and she looked so awkward.”