Barbra Streisand has reworked her 2014 song I'd Want It to Be You as a new duet with Willie Nelson.

The iconic entertainer had initially reached out to the country music legend to appear on the track for her 2014 duets album Partners, but ended up recruiting Blake Shelton to join her in the studio as Nelson's part wasn't ready by her release deadline.

Now, Streisand has finally unveiled the Nelson collaboration, which will feature on her new rarities project, Release Me 2.

The compilation will pull together previously unreleased songs from Streisand's music vault, such as Be Aware and One Day (A Prayer), as well as If Only You Were Mine with Barry Gibb, and Rainbow Connection with Kermit the Frog.

Also included is a cover of Carole King's You Light Up My Life and Randy Newman's Living Without You.

In the album notes, Streisand writes, "For me, the studio is a combination musical playground and laboratory... a private sanctuary, where the possibility of catching lightning in a bottle always exists.

"Whenever that kind of magic happens, it's extremely satisfying. Sometimes though, when the arrangement doesn't quite gel or the song no longer fits the tone of the album it was meant for, the tapes go into the vault for safekeeping.

"Working on this 2nd volume of Release Me has been a lovely walk down memory lane," she adds. "A chance to revisit, and in some cases, add a finishing instrumental touch to songs that still resonate for me in meaningful ways."

Release Me 2 is set to hit retailers on 6 August - nine years after the original project was launched.