Grohl attempted to bring the two acts together on a track for Sound City, his documentary about the California music studio where his band Nirvana recorded landmark album Nevermind.
He explains, "I was this f**king close to getting them on a record. I thought it was going to happen, it would've been f**king huge."
Manilow agreed to take part, but Grohl admits the Mandy hitmaker was hard to find, adding, "He was the first person who said he'd do it but was the last we tracked down. And we had to fly to f**king Hawaii."