Will and Britters were at No 2 in the midweek Official UK Singles Chart with Scream & Shout - a track which The Sun reports was originally recorded by Tulisa after she co-wrote it with Will's regular collaborator Jean Baptiste.
And Britney's British-tinged accent in the electro pop number is held as evidence that she was simply asked to copy Tulisa's part in the track - which had originally been titled "I Don't Give A F***" - and slated for Tulisa's The Female Boss album.
A source told the paper: "The song was due to be Tulisa’s third single from her album until Will told his protégé Jean that he wanted the beat for him and Britney.
"Tulisa's team thought it was a surefire hit but, after losing the battle for the rights, they were forced to release Sight Of You which only got to No 18.
"She now has to watch on as the song goes Top 5 around the world. At one point Tulisa was even considering releasing her version to rival Scream & Shout, but now it’s unlikely to see the light of day unless it gets leaked."