Sir Paul McCartney hates collaborating with other pop stars - because they are never as good as his former Beatles bandmate John Lennon.
The 64-year-old rocker has teamed up with Stevie Wonder and Michael Jackson in the past, but admits the duets don't match up to the standard of his songwriting efforts with Lennon.
MCCartney says, "I'm a little bit wary of collaborating with other people because it doesn't happen as easily or as amazingly as it did with John.
"It's a funny subject the collaboration thing (is) because I collaborated with John and you're a little bit spoiled after that. That was one hell of a collaboration. I've done it quite a bit since and, I think - and I hate to say it - there's inevitably a sense of disappointment because it was just so cool for John and me to be working together, because we started so young and knew each other's ways and minds."