The X Factor judges Gary Barlow, Louis Walsh, Tulisa Contostavlos and Kelly Rowland will tonight be forced to kick one of their own acts off the reality show.

In a shock twist to this year's contest, it will be down to each mentor, rather than the public, to pick one of their four hopefuls to leave after just one live performance.

The 16 hopeful acts last night battled it out to save themselves on the Britain vs America-themed show.

Following their performances Chorley soldier Jonjo Kerr was favourite in the over 25s to be the first in his group to go.

Although the judges were not vying for the public vote, the claws were out on the panel with Contostavlos and Barlow rowing about some of the performances.

The N-Dubz star told Barlow that she was going to show him her feisty side and called him "mental" after he expressed a critical view of boyband Nu Vibe's version of Chris Brown's Beautiful People.

The judges also had differing opinions about Essex duo 2 Shoes.

Wearing matching sequinned outfits, Charley Bird and Lucy Texeira sung the Girls Aloud party track Something Kinda Ooh while in a pink convertible on stage.

Barlow said the performance was akin to "karaoke night in Romford", leading Contostavlos to tell him to "give it a rest" adding: "You don't know how to have fun Gary."

Another act which left the panel divided was 45-year-old Johnny Robinson, who performed a bizarre version of Believe by Cher.

Barlow told the singer, who was wearing a silver outfit with matching sunglasses, that his performance was "cheap".

"Along comes Louis Walsh, he has absolutely turned you into a circus act," said the Take That star, who appears to have taken the helm in Simon Cowell's chair.

Walsh retorted: "Gary, you are missing the fun. This man is living his dream. The great thing about The X Factor is that it gives someone like Johnny a chance."

However, the judges had firmly united opinions about some of the performers - particularly the singers in the girls category - mentored by Rowland.

After Misha B, 19, from Manchester, performed Rolling In The Deep by Adele, Barlow hinted to Rowland that he was jealous of her contestants.

The 5'1" student, donning an unusual outfit made of newspaper, performed a rap in the middle of the song.

Contostavlos told her: "You are definitely the person that stands out the most in the competition. You really bring it when you step on that stage."

Petite Janet Devlin also impressed singing Coldplay's Fix You.

Contostavlos told her she was "mesmerising" with Walsh adding: "You've got celtic soul, you've got the voice of an angel."

Barmaid Sophie Habibis sung a slow rendition of Katy Perry's Teenage Dream while sitting on a white baby grand piano with smoke rolling across the stage.

Walsh told her: "You have got an amazing recording voice - which is what we're looking for on this show."

Girlband Rhythmix also impressed, singing Superbass by Nicki Minaj. The group, who were put together at Bootcamp, were told that they were the best girlband which has ever been on the competition.

Each judge will tonight put three of their four acts through to next week's show.

Barlow warned serving soldier Jonjo Kerr that he may be one of the acts who faces the chop.

The 27-year-old from Chorley, Lancashire, failed to win over the panel by singing You Really Got Me.

Another act who did not live up to her reputation was Kitty Brucknell.

The 26-year-old put on a "captivating" version of Queen's Who Wants To Live Forever, but she did not put on a eccentric show like her previous performances.

Sophie Habibis is 4/7 favourite with bookmakers William Hill to be the first girls to leave, while James Michael is the favourite boy ay 1/7, Jonjo Kerr is the favourite in the over 25s category at 1/6 and 2 Shoes are 1/3 on to be the first group to go.

The results show, which will feature last year's winner Matt Cardle and Cee Lo Green, will be on ITV1 at 8pm.