Stars set to duet with 'X Factor' finalists

Christina Aguilera, Robbie Williams, will.i.am and Rihanna are set to sing duets with ‘The X Factor’ finalists on Saturday night.

The international stars have each reportedly agreed to be paired up with hopefuls Cher Lloyd, Rebecca Ferguson, Matt Cardle, and boyband One Direction in a bid to help them win the hit ITV1 show.