(Cover) - EN Showbiz - RedOne says working with Lady Gaga and Cher on their duet was a "party".

The producer teamed up with the pair on their highly anticipated track, which Cher confirmed in August. He explained The Greatest Thing was actually recorded by Gaga several years ago, but Cher loved it when she heard it.

Gaga was initially happy for the iconic singer to work on the song on her own, before RedOne suggested it might be duet material.

"I cut the vocals with Cher first, and I was in Madrid and got a text from Gaga saying, 'I'm thinking about jumping on the song in the remix,'" he told MTV News. "I was like, 'No, you should jump on the original! Make it a duet.' She said, 'Oh yes, OK, absolutely,' and then I spoke to Cher, and it became a party.

"Everybody loved it. Gaga on it, Cher, two big icons, [they are] part of music history. So it happened. I'm very happy to be a part of this."

Cher has said The Greatest Thing will be out this month, but it's still not known exactly when. RedOne is staying tight-lipped about when it will hit airwaves, but is convinced it'll be a big hit.

For the producer, simply getting the opportunity to meet Cher was enthralling. He's been a big fan of hers for years and was overcome with emotion when he realised she wanted to work with him.

"I remember my management and Cher's management were trying to get us together, and I thought, 'Oh my God, I'd love to meet Cher, just to meet her!' And so I met her, I played her some songs, and I played her The Greatest Thing, and she loved it. She said, 'This is my song,' I said, 'Yes, it's your song,'" he recalled. (C) Cover Media