Simon Cowell is back on UK X Factor... but it's for one episode only +live discussion

No more Mr Nice on the X Factor.

Mr Nasty Simon Cowell will be back on our screens in the U.K. version on Sunday night, for the first time since leaving the show two years ago.

However, viewers hoping for more acid-tongued appraisals of British singing wannabes will be disappointed. 

The music mogul won't be returning to the judging panel, but will instead be seen letting Gary Barlow, Louis Walsh, Tulisa Contostavlos and former Pussycat Doll Nicole Scherzinger know which category they will be mentoring this season.

He will deliver the news in Sunday's episode, but the busy music mogul won't be telling them in person.

Viewers of the ITV series will see Cowell phone the judges from Miami during a break from filming the U.S. version of the show.

It will be the first time he has appeared on the show since quitting last year to work on the American version. 

The 52-year-old reality star didn't make an appearance at last year's show, but he did appear on ITV2 spin-off The Xtra Factor via satellite link.

His calls provokes a mixed response from the judges after finding out which groups they are in charge of.

Tulisa Contostavlos shouts 'Get in there!' after landing the girls category, while Gary Barlow is delighted with being in charge of the over-28s.

Louis Walsh was also pleased at being told he will be be mentoring the groups.

However, Nicole seemed initially shocked when she learned she is in charge of the boys category.

Viewers will hear her saying: 'I wasn’t expecting that. But I’m super-stoked. I think we have a real contender, possibly the winner of X Factor.'

While all talk is of Mr Nasty's return, there is also sure to be plenty of drama as the remaining Boot Camp acts are cut to 24.

Those that are selected will then be whisked to the judge's houses.