Britney Spears performs her hit Womanizer - Courtesy The X Factor ITV1
Britney Spears is gearing up for her first UK television performance in four years, on ITV1 talent show X Factor.
The 27-year-old will sing her current hit, Womanizer, while the show's five remaining contestants will each perform a track from her back catalogue.
However, the star will not coach the contestants, unlike previous guest stars Take That and Mariah Carey.
With the show down to its final weeks, the act leaving the competition will now be chosen solely by public vote.
Last week, judges sent 25-year-old Rachel Hylton home after votes placed her in the bottom two with boyband JLS.
Judge Simon Cowell, who had the deciding vote, told the mother-of-five he was a fan of hers but she had been in the sing-off three times.
Spears is on a whistle-stop tour of Europe ahead of the release of her latest album, Circus, on 1 December.
On Thursday she performed at an awards ceremony in Germany, where she was named best international pop star. On Friday, she sang on French TV show Star Academy.
The X Factor's creative director, Brian Friedman, has worked on several of Spears' tours and music videos - and promised she would have a few surprises up her sleeve for her UK appearance.
"She is going to be doing a massive performance," he said,
"You know her album is called Circus, so we're going to be seeing a circus vibe coming in".
He added: "I wouldn't be surprised if there were elephants because this is The X Factor - and we go big here!"
Spears' performances are being hailed as a comeback after a troubled year
Finalist Alexandra Burke, who will be singing Spears' hit single Toxic, said she was looking forward to the star's British appearance.
"When I was nine, Britney brought out Baby... One More Time, and I loved her," she said.
"I looked up to her because she had so much energy on stage. I'm very excited about meeting her. I hope I can do my Britney song justice, with my own twist."
Bookmakers' favourite Diana Vickers will sing I'm Not A Girl, Not Yet A Woman, while boyband JLS take on Baby... One More Time.
Spanish bombshell Ruth Lorenzo will sing I Love Rock 'n' Roll - the Arrows song later covered by Joan Jett and Britney herself.
Sixteen-year-old Eoghan Quigg, from Dungiven in Northern Ireland, is due to perform Sometimes.
Each of the contestants will also have to perform another song - which must be American - but their choices have been kept under wraps until the live show kicks off at 1935 GMT.
Meanwhile, Hannah Montana star Miley Cyrus will also take to the stage to play her latest single, 7 Things.