Speculations have started about which celebrities will appear in this year’s X Factor final to perform a duet with the contestants.

It is believed that the line up will include Rihanna, Robbie Williams and will.i.am.   According to The Sun, the three singers will join Christina Aguilera as rumoured yesterday to perform alongside this year’s four finalists in Saturday’s final show!

The newspaper claims the global stars will perform well known tracks with the finalists, but does not suggest which finalist will be paired with which star.

Yesterday, it was reported by Metro that Christina Aguilera will be singing with Matt Cardle. A source said:: “A duet between Christina and Matt would be a magical moment – just like when Beyoncé dueted with Alexandra Burke during 2008′s final.

“Matt’s voice is phenomenal and Christina can hit notes no-one has dreamed of. They would be a perfect pairing no matter what song they sang.”

It’s highly likely that, if true, will.i.am will be singing with Cher Lloyd. The Black Eyed Peas star said: “To me, Cher is like running with apples and oranges. It’s like apples and coffee beans. It ain’t even the same thing.

“You can make apple juice with apples but there is only one thing you can do with a coffee bean: make coffee.”

It is believed that Rihanna will be singing with One Direction while Robbie Williams returns to the stage after dueting with Olly Murs last year to sing with Rebecca. However, Rebecca had said previously she would love to duet with Whitney Houston.