Lady GaGa wrote the song she has just recorded with Cher years ago - but it was too big a tune to release on her albums.
The pop superstars have teamed up to record The Greatest Thing for Cher's new album and Gaga insists it was always destined to be a big duet hit.
She tells MTV News, "I wrote that song a long time ago, and I've never put it on one of my own albums for, really, no particular reason. I always write these concept records, and it just didn't fit in. But it's always been, like, this big, massive, beautiful hit record and everyone always says, 'Why don't you put that on your album?' And I said, 'I don't know, it just doesn't fit with everything else.'"
When Cher heard the track she asked if she could record it with Gaga.
The Poker Face singer says, "Cher heard the song and loved it and wanted to do it together, and I said, 'F**k yeah, it's Cher!'"
Reports suggest the two colourful pop superstars will perform the song publicly for the first time at the Mtv Video Music Awards on Sunday (28Aug11).