Michael J. Fox joined Coldplay on stage at the Glastonbury Festival in the U.K. for a surprise appearance on Saturday.

The "Back to the Future" star shared photos from the event on Instagram, thanking the band for the experience.

"My team: Lauren, John and Jeff and Steve… Glastonbury all the love and thanks to the @coldplay team who took such great care of us. And many thanks to Chris, Will, Johnny, Guy and Phil," Fox wrote in the caption.

He continued, "Oh yeah in case you were wondering… it was f---ing mind blowing. There is a time for every band and a band for every time. This is @coldplay’s time."

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Side by side photos of Michael J Fox and Chris Martin

Michael J. Fox made a surprise appearance at the Glastonbury Festival in the U.K., joining Coldplay onstage for a couple of songs. (Jesse D. Garrabrant/Joe Maher)

Fox shared a photo of himself in a wheelchair on stage with his team, as well as a photo of himself in front a sign that said, "optimism is a political act" and a quick video of the band walking backstage.

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According to Variety, Coldplay lead singer Chris Martin introduced Fox on stage before playing their song "Humankind," saying, "With his Chuck Berry riff and the way he punched Biff: ladies and gentlemen, please welcome Michael J. Fox."

Video shared by BBC Music on YouTube showed Fox stayed on afterward and played along on guitar from his wheelchair during the band’s performance of "Fix You," as Martin knelt beside the actor for portions of the performance.

Chris Martin and Michael J. Fox posing together

Chris Martin, with Michael J. Fox at the 2013 A Funny Thing Happened On The Way To Cure Parkinson's event benefiting The Michael J. Fox Foundation for Parkinson's Research. Martin credited Coldplay's existence with Fox's most iconic movie, "Back to the Future." (Dimitrios Kambouris/MJF2013/WireImage)

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After the song, Martin thanked the crowd, and added, "Especially thank you to the main reason why we’re in a band, is because of watching ‘Back to the Future,’ so thank you to our hero forever, and one of the most amazing people on earth, Mr. Michael J. Fox. Thank you so much Michael… hero."

Coldplay also shared the video on their official Instagram page, writing, "Thank you Michael J. Fox for making our dream come true."

Fox has previously appeared with Coldplay, joining them during a concert at MetLife Stadium in New Jersey in 2016, where they performed "Johnny B. Goode," the Chuck Berry song featured in "Back to the Future." 

Michael J. Fox and Chris Martin on stage with guitars

Fox appeared with Coldplay in 2016, performing "Johnny B. Goode," the Chuck Berry song featured in "Back to the Future." (Kevin Mazur/Getty Images for Atlantic Records)

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The "Spin City" star has been battling Parkinson’s disease since he was diagnosed in 1991.

In April, the 63-year-old was on Time’s "Most Influential People" list and received a touching tribute from fellow Canadian-born star Ryan Reynolds, thanking him for championing research and supporting others suffering from the disease, including his dad.

Micahel j Fox and Ryan Reynolds hugging

In April, Ryan Reynolds praised Fox, writing a tribute for Time's "Most Influential People" list. (Stephen Lovekin/Getty Images)

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"I’ve watched him raise the bar for purpose and passion," Reynolds wrote. "It’d be kinda lazy to simply characterize him as the greatest champion of Parkinson’s research on the planet. He’s someone who helped my dad, along with millions of others, feel less alone. It’d be kinda lazy to simply regard him as a movie star who shaped the lives of people all over the planet with a uniquely electric wit and self-aware charm. He’s the sum of these beautiful parts."