BOSTON -- There the Red Sox were late Monday night, a clubhouse full of grown men, awash in champagne and performing a hearty sing-along to a tune that you wouldn’t really expect to become the anthem to a baseball team.

But as anyone who saw the video of these joyous Sox singing -- roaring was more like it -- along to “Dancing on My Own” could tell, this was bringing them joy in the aftermath of beating the Rays in a hard-fought American League Division Series.

The version that was playing in that winning clubhouse, you should know, is the Calum Scott/Tiësto remix.

The artist who came out with the original version in 2010 is Robyn, and she was so excited about the Red Sox singing her song that she tweeted about it.

So how exactly did “Dancing on My Own” turn into the theme song of a Boston team that is now just four wins from getting to the World Series?

To answer that question, you need to talk to catcher Kevin Plawecki, who has been using Scott’s version as his walk-up song at Fenway Park for the last two seasons.

The origin of this song spreading like wildfire includes not just Plawecki, but also three players who no longer wear a Red Sox uniform in Andrew Benintendi, Kevin Pillar and Mitch Moreland.

Allow Plawecki to explain.

“Spring Training 2.0, when we all came back to camp [last year],” Plawecki said. “We were driving home from golf one day or something like that. I lived with Benintendi and Pillar. Me and Benny and Pillar we’re in the car and the song came on and I was like, ‘What song is that?’”

Benintendi was the only one in the car who knew.

“Benny told me. From then on, me and Benny and Pillar and Mitch Moreland lived together last year and we just played this song all the time,” Plawecki said. “It was kind of as a joke, because Moreland didn’t really care for it. He’s a country boy and was like, ‘This song sucks, yada yada.’”

Moreland’s disdain was enough for Plawecki to have some fun with it during an intrasquad summer camp scrimmage last July.

“We had a scrimmage game and we had walk-ups for the scrimmage,” Plawecki said. “I’m like, ‘I’m just going to mess with Mitch today.’ He was on the other team playing first. So my first at-bat with it as my walk-up song, I hit a homer and I’m singing it to Mitch as I’m running around first, and then, I obviously kept it as my walk-up for the whole year last year and then throughout this year.

“I’m always playing music on the speaker, on the bus and stuff. Everybody’s like, ‘Play that one song.’ So I always play it. Everybody has just gone overboard now. I never would have thought everyone would sing it like that.”

When the Red Sox clinched their AL Wild Card spot in Game No. 162 against the Nationals, the song was of course part of the winning soundtrack in the clubhouse.

But the team didn’t take it to the next level until the Sox beat the Yankees in the AL Wild Card Game at Fenway Park two days later. That’s when they first went into full Karaoke-mode (no titles needed).

And there they were again on Monday night against the Rays, at full-throat to the song that will be remembered forever by Red Sox fans if they keep winning this October.

“Plawecki’s the one who always walks around with the speaker. He’s got about five songs in rotation,” left fielder Alex Verdugo said. “Doesn’t matter if it’s a four-hour flight or whatever, you’ll hear the same five songs. For some reason, this dude really loves that song, ‘Dancing on My Own.’

“Sure enough, it just kind of went from, he played it and guys were like, ‘All right, we like it.’ Then it was like, ‘Dang, he’s overplaying it. We’re kind of done with it.’ Now it’s our song. This is what we’re turning up to. He’s played it so much that all the guys know it. Plawecki’s a good teammate and fun dude. It’s one of those things that just originated on his end.”

Recent Red Sox World Series championship teams have similarly adopted songs to unify the team.

In 2013, it was “Started From the Bottom” by Drake, an obvious reference to Boston’s last-place finish in 2012.

The team’s unifying October song in 2018 was accidentally created by Aaron Judge, the Yankees slugger who played Frank Sinatra’s “New York, New York” on his speaker as he walked by Boston’s clubhouse after his team won Game 2 of the ALDS.

When the Sox ousted the Yanks in four games in that series, they must have blasted that Sinatra song on endless loop for hours in the visitors’ clubhouse. And they repeated the ritual after beating the Astros in that year’s ALCS and the Dodgers in the World Series.

“Fun, silly stuff that organically happens. Keep it light, keep it fun,” Plawecki said.