They are musical giants.
Phil Collins and Paul McCartney are the only two living musicians - Michael Jackson was the third - to have sold more than 100 million records both as a solo artist and as part of a band.
And yet when the pair met, Collins was distinctly unimpressed.
The 65-year-old Genesis frontman, who announced this week that he was coming out of retirement, spoke of his shock when he came face to face with the former Beatle.
"I've got to preface this by saying McCartney was one of my heroes," he told The Sunday Times.
"But he has this thing when he's talking to you, where he makes you feel: [putting on a condescending Scouse accent] 'I know this must be hard for you, because I'm a Beatle. I'm Paul McCartney and it must be very hard for you to actually be holding a conversation with me.'"
Collins told how the pair had met in London.
"I met him when I was working at the Buckingham Palace party at the palace thing back in 2002.
"McCartney came up with Heather Mills and I had a first edition of The Beatles by Hunter Davies and I said, 'Hey Paul, do you mind signing this for me?'
"And he said, 'Oh Heather, our little Phil's a bit of a Beatles fan.'
"And I thought, 'You f---, you f---.' Never forgot it."
Collins will play five nights at London's Royal Albert Hall next summer, as well as dates in Cologne and Paris.
The In The Air Tonight singer officially retired in 2002.
He then divorced his third wife, Orianne Cevey, in 2008 - paying her £25m in what was then Britain's largest divorce settlement.
Collins turned to drink, as his ex-wife left their Geneva home, moved to Miami with their two boys, and remarried.
But her marriage fell apart and she is now reunited with Collins - the pair living in Jennifer Lopez's former house in the Florida city.
Of his retirement, he said on Monday, at a press conference to announce his return: "I've changed my mind. I'm living with my young kids.
"They want me to go out on the road and do my thing, and why not?"