Above video comes courtesy of “A BEAUTIFUL NOISE ON BROADWAY” via FOX NewsEdge.

(WGHP) — Theatergoers got an unexpected, once-in-a-lifetime show from legendary singer-songwriter Neil Diamond on the opening night of the new Broadway musical “A Beautiful Noise.”

The musical, which opened at the Broadhurst Theatre on Sunday, tells the story of Neil Diamond from growing up in Brooklyn through his rise to fame.

The show stars actors Will Swenson and Mark Jacoby as Diamond “then” and “now,” but, the audience, to their shock, also got a performance from the 81-year-old legend himself.

According to People, Diamond offered an impromptu performance of “Sweet Caroline” during the curtain call in what was his first hometown performance since 2017.

A video shared by the musical’s official Instagram shows the view from the floor. As the music to “Sweet Caroline” began, the crowd was looking to the stage and humming along. Diamond, standing at his box seat, then begins singing the lyrics. In a wave of surprise, heads in the audience turn to Diamond. The singer, the cast and the audience sing together before closing out with raucous applause.

Diamond announced his retirement from concert touring in 2018 following his Parkinson’s diagnosis, making his appearance all the more special.

“I plan to remain active in writing, recording and other projects for a long time to come,” Diamond said in a statement announcing his touring retirement. “My thanks goes out to my loyal and devoted audiences around the world. You will always have my appreciation for your support and encouragement. This ride has been ‘so good, so good, so good’ thanks to you.”