NEW YORK - Kanye West and Paul McCartney, two music legends from opposite sides of the track, have teamed up in an unlikely collaboration on a new single released Thursday called "Only One".
The soft ballad, which West said was inspired by his daughter, features the vocals of the world-famous rapper and former Beatle McCartney on the organ.
The lullaby-like collaboration has been in the works since early 2014, when the two met in a bungalow in Los Angeles, according to a statement from West's label Def Jam recordings.
"The process that would result in 'Only One' began with a simple brainstorming session between the two, with McCartney improvising on the keyboards and Kanye vocally sketching and shaping ideas in a stream-of-consciousness riff," it said.
The song was inspired by West's daughter North, who was sitting in his lap when he sang to her "Hello my only one".
West said his own mother used to sing those words to him as a child.
"My mom was singing to me - and through me - to my daughter," said the hip hop artist, whose first name also means "only one".
Def Jam called the collaboration "one of the most powerful and unexpected music collaborations in modern history".
The single was released late New Years Eve, and will be available on iTunes in 119 countries for one week.
West, 37, is married to US reality television star Kim Kardashian, who sent a tweet about the new tune to her 27 million followers.
"People always ask me what my favorite Kanye song is and it's Only One. Kanye feels like his mom sang thru him to our daughter," Kardashian wrote on Twitter.
"I cry every time I hear this song," she wrote.
West has frequently paired up with other musicians - from rapper Jay Z to British rockers Coldplay - on his albums.
Liverpool-born McCartney, one of two surviving members of the Beatles, continues to play music and tour around the world.
This is the first time the duo have worked together on a song.