The Girls Aloud singer, currently single, is said to have grown close to The Voice UK star when working on her new album due for release later this year.
Cheryl met Black Eyed Peas star Will back in 2008 when she featured on his solo track Heartbreaker, and the pair have stayed in touch ever since.
The US star has featured on her first two studio albums, and is also set to appear on her new record which is slated for release in the summer.
A source says: "They've grown really close - they talk all the time and there's always been chemistry between them.
"They’ve been exchanging flirty messages since she watched the first show [of The Voice UK]. Cheryl though he was looking really good and told him so."
Speaking to Closer magazine, the supposed pal of the pair goes on: "She hasn’t' been able to spend much time with him recently, but once the live shows start, he'll be able to see her more.
"It's clear she likes him - Will gets her undivided attention whenever he's around and her contact with Ashley [Cole] and Derek [Hough] has dropped off."
But Will is hoping to keep any potential romance out of the papers and magazines (a bit too late for that, it seems), and is planning on "smuggling" Cheryl on and off The Voice UK set later this year.
"Cheryl and Will really click and now she's telling friends she thinks she could fall for him," the friend goes on.
"Will and Cheryl have been discussing ways to smuggle her on and off the set of Th Voice so she can be there regularly."