Stefani: Eminem collab barely happened

Gwen Stefani claims her track with Eminem "barely" happened.

The 45-year-old songstress collaborated with the 42-year-old rapper on their new song Kings Never Die, a tune they recorded for the soundtrack of forthcoming boxing drama Southpaw.

But when she first learned of the project, Gwen didn't think she could do it.

"The process was really simple. One of his guys came and played me the song and then I was like, 'Yeah, I like it! Amazing!'" she recalled to Entertainment Weekly of how the collaboration came about.

"I've always wanted to work with him — he's a genius — and then all of a sudden they called me and said, 'It has to be done today' and I was like, 'Ah, my voice' — I had a cough or something. I went in and I made it happen, but it was like, barely."

At first, Gwen couldn't believe her luck, as she didn't want to record anything with a scraggly voice.

But the Hollaback Girl star is now happy with how the song turned out.

"It was like, 'God, why does today have to be the day my voice is not happening?' But it ended up turning out good," she noted. "I wanted to do something with him for so long and I feel honoured — he's very selective. I feel really honoured."

Gwen and Eminem's tune Kings Never Die was released on Friday July 10. The movie Southpaw, which stars Jake Gyllenhaal, Forest Whitaker and Rachel McAdams, hits US theatres July 24.