The X Factor's Rita Ora called fellow judge Simon Cowell "rude" as the pair clashed over contestant Katie Coleman during the Six Chair Challenge.
In the explosive episode, viewers will also see the X Factor supremo throw a strop and utter an expletive after being voted mentor to the Overs.
The spat between the two panellists occurred following the 21-year-old's rendition of Christina Aguilera's The Voice Within. TV mogul Cowell said: "You were better the first time, but if it was me, I would give you a chair."
The crowd believed this was a positive assessment and cheered. However, he clarified his statement: "Not one of those. I'd give you a chair at home. I don't think it was good enough."
Cue boos from the Wembley audience and stunned looks from the panel. Ora fired back: "That was just rude." She added: "Simon if you would just like to mind your own business and wait until your category comes up!"
The X Factor head judge was unrepentant and insisted he was right, but the Darlington singer's fate rests with the 24-year-old panellist now mentoring the Girls.
The stakes are high at this controversial stage of boot camp as each judge whittles their category down to six acts by granting one a seat on stage if they're considered good enough.
The drama begins when all six seats are taken because if a better choice comes along, a seated contestant can be swapped out of their seat - and possibly out of the ITV competition for good.
In a first for The X Factor, the public had their say as to the categories each judge would be mentoring. BBC Radio One's Nick Grimshaw is in charge of the Boys, while Cheryl Fernandez-Versini is somewhat out of her comfort zone with the Groups.
But Cowell did not hide his dismay after being voted the mentor to the Overs: as many of the hopefuls watched, he swore out load. "Oh, f***! Are you winding me up?" he said.
Ora's Girls have to take the challenge first. "In my eyes, the winner of The X Factor is in this group, but you're going to have to bring it. Just bring it," she instructed.
All eyes will be on 25-year-old youth worker Monica Michael who has returned to the singing show after she was booted out during the six-chair challenge by Fernandez-Versini.
"Last year I was in Cheryl's category at this point," she said. "It's the craziest thing because you're so excited to go on there and sing your song, but at any point your dreams can vanish just like that.
"I don't think I was ready last year, but going home and not getting a chair this year, that scares me. It really does because I know the feeling."
Viewers will have to wait and see if the Londoner's rendition of What Is Love by Veronika Bozeman is enough to earn her a seat.
Among a number of acts hoping to impress Ora will be 17-year-old student Charli Beard, 21-year-old sales assistant Havva Rebke and 25-year-old dental receptionist Lauren Murray.
The X Factor airs on ITV at 7pm today.