Forty thousand exuberant fans had made their way to their seats before England was set to play Germany at legendary Wembley Stadium during the 2021 Euros. DJ Tony Perry knew exactly what song he wanted to play to get the crowd going: Neil Diamond's "Sweet Caroline."

It was a triumphant moment that soon went viral -- especially as England defeated Germany, 2-0, en route to a trip to the Finals, where they were defeated by Italy. The song became synonymous with the Three Lions -- as England's soccer team is called -- and has since become a staple at soccer matches around the country.

"I was absolutely not prepared at all," Perry told MLB.com in a recent phone call about the fan reaction. "It was really maddening because we were just coming out from the backend of COVID. We were having to perform with our PPR face masks on and when I played it, both sets of fans actually started singing it because the Germans sing it at Oktoberfest. I literally muttered the words, 'Oh my god,' under my face mask."

And who's to thank for this? Why, the Boston Red Sox, who play it in the eighth inning of every home game, of course.

Perry has been playing R&B and hip-hop at clubs in the UK for over a decade, but in recent years has started playing more sporting events. He began with rugby, and was the stadium DJ at the 2021 Euros and at this past fall's World Cup. He was well acquainted with the Neil Diamond hit -- admitting that it had been played at soccer games before the Euros took it to new heights -- but had only played it once in his DJ career. That was at a friend's wedding in Ireland in 2016. It just wasn't the type of song that he really associated with getting people up and out of their seats.

And then the 2019 London Series came, where Perry was a guest DJ. Perry would offer up the occasional track with organist Ray Castoldi handling most of the music and entertainment duties at London Stadium for the weekend. Perry was then taken aback when Castoldi told him not to play "Sweet Caroline."

"Don't play this record," Castoldi told Perry, "because we're gonna play it."

"I was like, 'Mate, I was never gonna play that anyway,'" Perry remembered with a laugh. "Why the hell would I play 'Sweet Caroline'? And then he played it as I was leaving the stadium and it just echoed and reverberated. I was like, that is powerful. That's incredible."

The fan reaction stood out to Perry. Even in England, a country that loves to sing at its sporting events -- West Ham, who are the usual tenants of London Stadium, are known for "I'm Forever Blowing Bubbles" -- couldn't resist Diamond's catchy hit.

"Without that moment, I wouldn't have played it at the Euros where it became a thing in English culture. It stemmed from the London Series -- and that's a fact," Perry said. "Up until 2019, it was just another record. But then at the Euros in 2021 after I pressed play when England played Germany, that's when it went ballistic. It got to number three on the international charts."

Perry will be back at the London Series this weekend when the Cubs and Cardinals play each other, but he's staying mum on what discs he plans to spin. Surely there will be Steve Goodman's "Go Cubs Go," but as for what else? That's a mystery. The one hint is that he'll play something the fans can chant along to.

"For me, there's like a point system in how you can rank the songs and chantability has to be the number one [criteria]," Perry said. "If it's something that's easy that you can sing along to that is the key thing. That's going to make or break it in terms of the fan engagement, 110 percent."