An X Factor twist has been revealed – judges will have to eliminate four hopefuls this Sunday.

The judges will have to pick one member of each category – the boys, the girls, the over 25s and the groups – to leave.

A quarter of the 16 finalists will be eliminated, in a twist promised by producers to keep the show “fresh” and make sure the performers “step up a gear during the live shows”.

The contestants will be trying to impress the judges rather than viewers, as there won’t be a public vote this weekend.

Head judge Gary Barlow: “We thought rather than wait until Saturday night we'll talk about the twist. This is The X Factor stage – it’s one thing singing by the pool but it all changes here.??

“This is where stars are born, like Leona – it’s all going to feel very different on Saturday."

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The judges will make their decision solely on Saturday’s performances before the unlucky four are revealed in Sunday’s show.

Kelly Rowland told the performers: "We want you to put your best foot forward, make the decision hard for us and let us know why you need to stay."

Louis Walsh said: "It’s a level playing field – we want to see your passion, we want to see a star, it’s all to play for."

And Tulisa Contostavlos added: "Please understand all of you that none of us have made our decision. It’s a clean slate and we are m.aking our decision as if we have never seen you before."?

The show starts at 7.30pm on Saturday and 8pm on Sunday, and this week’s theme will be UK v US.

Guest artists will be last year’s winner Matt Cardle and hip hop artist Cee Lo Green.