Sir Paul McCartney was left fearful as he thought a "girl fan" had got hold of his number - but it was actually Michael Jackson.
The former Beatles star, 79, admits he didn't recognise the King of Pop's soft voice and was convinced it was a "groupie" on the line.
The call left Paul "annoyed" as he thought it was a stranger trying to get hold of him.
He told Daily Star: "Somebody rang me up, and this high voice I didn’t recognise said, ‘Hi, Paul.
"I thought, ‘This is a girl fan, and how the hell did she get my number?’ I was quite annoyed.
"Then the voice said, ‘It’s Michael,’ and suddenly it dawned on me.
"It wasn’t a girl, it was Michael Jackson, and he basically said, ‘Do you want to make some hits?’”
After he found out he was speaking to music legend Michael, the pair penned Say Say Say together in 1983.
In recent weeks, it was revealed Sir Paul gets vocal with guitars – and talks to them.
The star said he felt sorry for one that hadn’t been played for a while and told it: “You must be lonely.”
Macca explained: “I felt quite guilty in a minor way, so I went over and started playing - and then the song that came out was me talking directly to the guitar and talking about all the times it had helped me.”
In new book The Lyrics by Paul McCartney, he said The Beatles used to tell their guitar their “secrets” and also thought it “looks like a woman”.
He explained: “There’s lots of stuff going on there.
“We always used to say that when you sit down with your guitar to write a song, you’re telling it your secrets, which then become a song for the world.
“But at that moment, when you’re alone, the guitar is your confidante. You cradle it.
“When you go up to a piano, though, it’s almost as if you’re pushing the piano away; they’re different actions completely.”
The member of the Fab Four also made a surprising comment in his new book where he discusses how The Beatles were not the "greatest band ever".
He revealed: “The biggest influence on John and Me was The Everly Brothers. To this day, I just think they’re the greatest. And they were different.
“You’d heard barbershop quartets, you’d heard the Beverley Sisters - three girls - you’d all heard that. But just two guys, two good-looking guys? So we idolised them. We wanted to be them.”
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