The beautiful theme written by Ennio Morricone for "Once Upon A Time In America" so moved songwriters Alan and Marilyn Bergman in 1984 they had asked the film’s producers to allow them to write lyrics for the song. They were nixed.
Fade into 2006; Alan Bergman tells me he got a call from Quincy Jones who is doing a tribute CD to the great composer Morricone.
Quincy tells the Bergmans, "I’d like you to write the lyrics to–" you guessed it — the theme from "Once Upon A Time In America." They did. They went to Las Vegas where Celine Dion recorded it. The song: "I Knew I Loved You — Before I Knew You."