Metallica's Robert Trujillo and Kirk Hammett gave Boston sports fans a treat Sunday night by leading a "Sweet Caroline" sing-along during the band's Gillette Stadium concert.

For over two decades, Neil Diamond's Top 5 1969 hit has been a fixture at Boston's Fenway Park, with fans singing along with the song in the middle of the eighth inning of every Red Sox game.

You can watch Trujillo and Hammett play and sing "Sweet Caroline" below.

"This song is really scary, super heavy and if you start moshing try not to injure yourself, because it's such a scary song I'm already shaking," Trujillo joked before launching into the performance. The crowd eagerly joined in, shouting "Bum, bum, bum" and "So good! So good! So good!" in all the right spots.

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Trujillo and Hammett regularly perform bass and guitar "doodles" at Metallica concerts, often choosing songs with connections to the city in which they are performing, such as Kansas' "Carry On Wayward Son" in Kansas and Grand Funk's "We're an American Band" in Michigan.

Metallica's 15-song Gillette Stadium performance was delayed by severe weather which forced the crowd to be evacuated from the stadium prior to the show. However, the venue's curfew was extended to allow the band to play a full set that wrapped up with "One" and "Enter Sandman."

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Watch Metallica Perform 'Sweet Caroline'

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Gallery Credit: Ed Rivadavia