In an Instagram video, the musical’s lead, “American Idol” winner Nick Fradiani, introduced Diamond, 84, who delivered an impromptu performance of his hit “Sweet Caroline” from the audience.

Neil Diamond surprises fans with rare performance 7 years after announcing retirement Neil Diamond visits "A Beautiful Noise" at the Hollywood Pantages on July 12.© Chelsea Lauren/Shutterstock ...

Neil Diamond made a rare and emotional appearance at “A Beautiful Noise” in L.A., leading a surprise sing-along of “Sweet Caroline.” ...

Neil Diamond Gives Surprise Performance of 'Sweet Caroline' for “A Beautiful Noise ”Audience The singer retired from concert touring in 2018 after he was diagnosed with Parkinson's disease ...

Video showed fans rising to their feet around Diamond, who was out in the crowd, microphone in hand to sing the song as part of his namesake, “The Neil Diamond Musical: A Beautiful Noise.” The ...

Tiffany Tatreau as Diamond’s first wife Jaye Posner, from center left, Nick Fradiani and Kate A. Mulligan as singer-producer Ellie Greenwich in “A Beautiful Noise.” ...

Dive into Neil Diamond's inspiring journey at 'A Beautiful Noise' musical in San Diego. Relive classics and support Parkinson's awareness. Don't miss the electrifying show!

Fradiani, 39, also posted footage from Diamond’s visit to the show with pictures of them posing backstage. “I built up this day in my head for over 2 years. The day where Neil Diamond himself ...