Cheryl Fernandez-Versini and Rita Ora think the groups on 'The X Factor' this year are "the best they have ever been".

The 'X Factor' judges

The 'X Factor' judges

After it was announced that viewers will now vote using Twitter hashtags to decide who the judges will mentor on the ITV talent show, the 'Poison' hitmaker and former Girls Aloud singer have shared how eager they are to work with the group category.

Cheryl said: "The groups this year are the best they have ever been. We have got three groups that I would take right now from their first audition straight through to the live shows."

Rita told the Daily Star newspaper: "For some reason the groups are so powerful, they are literally on fire."

'X Factor' boss Simon Cowell and the judging panel - Rita Ora, Cheryl Fernandez-Versini and Nick Grimshaw - will find out who the public have chosen for them to mentor during the six-chair challenge at London's Wembley Arena next week, and the music mogul said Cheryl is "terrified" about the new system.

Simon told the Daily Mirror newspaper: "She's terrified she's going to get stuck with one category and someone else is going to get a better one. She's so competitive, which doesn't work with me any more, by the way."

Meanwhile, the 55-year-old star believes there is "no weak category" this year and he can predict who will win from each.

He told the Daily Star newspaper: "There's no weak category this year. I can see who the winner of each category could be."