Dermot O'Leary says Louis Walsh is the "dirtiest" 'X Factor' judge.
The 41-year-old host has revealed that although judges Cheryl Fernandez-Versini, Louis Walsh, Mel B and Simon Cowell have been getting on well on the ITV talent show so far, he knows they won't hold back once they go head-to-head in the live shows later this year.
Speaking at 'The X Factor' launch at London's Ham Yard Hotel, he said: "I'm going to have my hands full when it comes to the live shows because up until now they're sort of all playing for the same team, they all want to find 12 great acts but when we get to the final I know they're all going to play dirty.
"Louis is the dirtiest of them all."
Cheryl and Simon are making their return to the show after a three year absence - during which Simon acted as a mentor on the US version - but they've confessed it feels like they never left.
Cheryl said: "It's like I've never been away to be honest. It's like the last four years never happened and we're back to square one."
Simon added: "[I feel] exactly the same way, it was like those four years disappeared, it was fantastic."
Louis - who has been a mentor for all eleven series - admitted there was a much better atmosphere between the judges this year, following the departure of Gary Barlow, Nicole Scherzinger and Sharon Osbourne.
He explained: "I think it's a different show, we're all having fun."
Meanwhile, Sarah Jane Crawford - who has taken over from Caroline Flack as presenter of the 'Xtra Factor' - insists Cheryl and Mel B have been getting on like a house on fire.
She revealed: "These two [Cheryl and Mel] are like besties by the way, they're always gossiping together."
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