Lady Gaga is delighted she held back an early song, as the "massive" and "beautiful" track is to finally be used for her eagerly-awaited duet with Cher.

The two eccentric pop stars are teaming up to duet on the song, titled The Greatest Thing, and Lady Gaga has revealed she has been waiting for the right time to use the track.

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.'

"Cher heard the song and loved it and wanted to do it together. And I said, 'F**k yeah, it's Cher!"