Many other acts are expected to duet on the night
Cheryl Cole is to duet with rock band Snow Patrol at this week's Children in Need's charity concert.
The X Factor judge will sing Martha Wainwright's lines from the Snow Patrol song Set The Fire To The Third Bar at the Royal Albert Hall on Thursday.
Frontman Gary Lightbody told the Spinner Music website that some people had "raised an eyebrow" when they heard about the collaboration.
The BBC has denied reports that Robbie Williams will sing with Take That.
The Sun newspaper said Williams, who left the band in 1995 to launch his solo career, would perform with Take That at the gig, which has been organised by Gary Barlow.
But a BBC spokeswoman said that was "categorically not true".
Speculation about Williams re-joining Take That has increased since the singer told Jonathan Ross on his Friday night chat show that there are plans for him to perform with the band again some time in the future.
The 35-year-old said: "We've got together, done bits and bobs. I can't say much."
Meanwhile, Lightbody said there were other unexpected duets planned at the charity concert.
"Everyone doing that gig has to duet with someone from the gig," he said.
"Everyone gets a partner, it was like getting a partner at school. We got the prettiest girl in the class.
"People have raised an eyebrow now and again when we've mentioned we're doing it with Cheryl Cole but I think it's going to be a really interesting experience."
In October, Barlow told Radio 1 breakfast show presenter Chris Moyles that each act would be doing two songs, but promised there would also be "three or four one-off duets that have never been seen before".
Other acts taking part in the charity gig include Muse, Sir Paul McCartney, Dame Shirley Bassey and Dizzee Rascal.