Keith Richards was blown away by Ed Sheeran when he supported the Rolling Stones.
The 'Satisfaction' group's guitarist initially thought it was a "joke" when the 'Shape of You' hitmaker turned up with his loop pedals to perform at the huge stadiums on their US 'Zip Code Tour' in 2015.
However, he ended up being mesmerised watching the 27-year-old singer/songwriter entertain the masses with his simple setup.
The 74-year-old rocker said: "Ed Sheeran was amazing, when he played with us.
"I thought it was going to be a joke because he had to go on at bloody great big stadiums in America and he came on with his two amps and his other things.
"But he was great, it was incredible to see actually.
"He's so clever - to be able to do that."
Meanwhile, Keith has been swapping "bland" drugs for an Instagram addiction.
The 'Start Me Up' band's drummer Charlie Watts explained to the Daily Star newspaper: "I can't believe Keith posted anything on Instagram.
"It's like if you ask him, 'What's your mobile number?' It's not Keith, it doesn't exist."
Keith is known for his wild partying ways but recently insisted these days his only vices are coffee and cigarettes.
He said: "Drugs are not interesting these days. They are very institutionalised and bland. And, anyway, I've done 'em all."
However, the ex-hellraiser admitted he isn't sure how long his sobriety will last.
He confessed: "I'm not saying I'm definitely off all of this stuff.
"In six months' time, I might be on it again. But at the moment, for a couple of months, I haven't touched it."
Asked how he finds abstinence, he laughed and said: "It's novel."
But the 'Gimme Shelter' hitmaker - who has four adult children, Marlon and Angela with late former partner Anita Pallenberg and Theodora and Alexandra with wife Patti Hansen - is unsure the sobriety of himself and bandmate Ronnie Wood has improved their musicianship.
He laughed and said: "Well... all things are relative! Insobriety produced some amazing stuff, too!"
The Rolling Stones bring their 'No Filter Tour' to the UK this summer, kicking off at London Stadium on May 22.