It's impossible not to sing along to "Sweet Caroline" — especially when Neil Diamond has the mic.

During the curtain call of the Saturday, July 12 matinee performance of A Beautiful Noise at the Hollywood Pantages Theatre in Los Angeles, the 84-year-old singer surprised audiences with an impromptu performance of "Sweet Caroline."

Nick Fradiani, who portrays Neil in the musical based on his life, introduced the legendary musician, who was seated in the orchestra section with a microphone in hand, ready to sing the 1969 song.

After his performance, Neil greeted the cast and company of A Beautiful Noise backstage and spent time with them. The musical's Instagram account called Neil's appearance, "a moment we’ll never forget."

Days before, during the curtain call of the Los Angeles opening night of A Beautiful Noise on Wednesday, July 9, actor Fradiani, 39, paused the standing ovation to surprise the audience.

"I’ve been doing this show for a long time now, and it’s still an amazing feeling to perform Neil’s songs for everybody. And we have a special guest here, a good friend of the show: Katie Diamond," he said, introducing Neil's wife.

“This is really a special day for me, because as I’m sure many of you know, if you’re a fan of Neil, that ‘The Jazz Singer’ was shot in this very venue for the live scenes. So it’s really special, actually, for me to stand here on this stage."

"It’s very exciting. Also, I do have Neil on FaceTime, so please welcome on stage Neil Diamond," Katie, 53, added, showing off her phone screen, which featured Neil. She held her microphone to the phone speaker for him to sing the 1969 hit.

Diamond has surprised fans with performances of "Sweet Caroline" through the years, including a massive sing-along in Times Square for New Year's Eve in December 2017.

He made an appearance at Fenway Park in June 2022, where the song is played during the middle of the eighth inning at Boston Red Sox Games, and at the Broadway show's opening night in December later that year.

The December 2022 performance marked the first time he had performed in his hometown since 2017.

In January 2018, Neil announced that he was retiring from touring after being diagnosed with Parkinson's disease.

"It is with great reluctance and disappointment that I announce my retirement from concert touring. I have been so honored to bring my shows to the public for the past 50 years," he said in a statement at the time.

"My sincerest apologies to everyone who purchased tickets and were planning to come to the upcoming shows. I plan to remain active in writing, recording and other projects for a long time to come."

"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."

In March 2023, Neil opened up about his Parkinson's disease diagnosis, saying that he had accepted it several years later.

"Somehow, a calm has moved in, and the hurricane of my life, and things have gotten very quiet, as quiet as this recording studio," he said during an appearance on CBS Sunday Mornings.

"And, I like it. I find that I like myself better. I'm easier on people. I'm easier on myself. And the beat goes on, and it will go on long after I'm gone."