A songwriter is suing Britney Spears for copyright infringement, saying he wrote the song Sometimes 15 years ago.
Sometimes appeared on Spears' debut album in 1999
Steve Wallace, 34, says he wrote the song in 1990, but did not formally copyright the track until 2003.
Alongside the complaint, filed at a federal court in Indianapolis, Mr Wallace submitted a copy of an e-mail allegedly written by pop star Spears.
In the e-mail, Spears allegedly admits that Mr Wallace wrote the song. Music label Sony/BMG have refused to comment.
The complaint cites Spears, album promoter Sony/BMG Music Publishing Inc and recording and publishing companies affiliated with the singer.
Mr Wallace claims that a few weeks after writing the track in 1990, he executed what's known as a 'poor man's' copyright, sealing his work in an envelope and obtaining a postmark.
The track was offered around to music publishers in 1994.
The lyrics of Sometimes are almost identical to those written by Mr Wallace, a side-by-side comparison submitted as evidence shows.
Spears, 23, obtained a US copyright for Sometimes in January 1999.
Mr Wallace's lawyer, John Ritchison, said he had previously tried to settle the case out of court.
Mr Ritchison said he wrote to Spears' lawyers seeking recognition and licensing or payment for his client, but they denied Mr Wallace's claim.
Sometimes appeared on Spears' 1999 debut album, Baby One More Time, and on 2004's Greatest Hits: My Prerogative.
Meanwhile, Spears has announced plans to produce a film set in the world of Nascar racing.
Trading Paint will focus on a pair of rival racing drivers who lose touch with each other following a horrendous crash, and the woman who brings them together for one final race.
The $55m (£30m) movie begins shooting next year. No cast has been announced.