"I was quite flattered," McCartney said. "I thought, 'Why does he want to work with me?'" Bringing on even more self doubt was the fact that after McCartney worked with Kanye it took a few months for the rapper to get back to him making him feel like a neglected girlfriend.

"It was a few months later when I was starting to think, 'Should I ring him and ask him did anything come of the stuff we did?'" McCartney explained. 'But then I thought 'I can't do that -- that's too soppy!' I'll just leave it and try and act cool. And suddenly he sends me 'Only One,' and then Rihanna's on the other record." The other record being "FourFiveSeconds."