Coop de Ville is the acknowledged go-to place for World Cup soccer. The Oak Bluffs dockside bar and seafood joint has draped flags from all 32 nations in the tournament over the outdoor patio, shipped in boxes of special-edition, three-liter Carlsberg beer cans and papered the walls with the World Cup bracket. The owners have seen nearly 40 games come and go. And they had known for nearly a month that the Group E match would be played on Wednesday afternoon at 2 p.m. They even brought a police officer.

But when Serbia is set to play Brazil, the two countries with the largest immigrant populations on Martha’s Vineyard, for a spot in the round of 16 at the most prestigious and historic soccer tournament in the world, you can only know so much. The rest, as they say, depends on how the ball bounces. And on Wednesday, oh boy did it bounce.

Gustavo Batista and son Lucca watch the Brazil vs. Serbia soccer match. — Jeanna Shepard

“It’s electric in here,” said Coop de Ville bartender Ben Brittle. “It’s hands down the busiest we’ve been.”

Vacationers on Circuit avenue wearing hoodies and toting ice cream cones were treated to chants, anthems and songs in languages they couldn’t understand, with tunes they couldn’t forget. Inside the bar, space was made and benches were cleared — not because of a brawl, but to prevent one.

Serbians, who made up about forty per cent of the crowd, prayed and sang, appealing to a higher order in the hope that it could help them overcome their meager chances against the Brazilian juggernaut. Brazilians, emblazoned in yellow and confident in their team, chanted back, letting the Serbians know that they had both God — and odds — on their side.

But minutes before the game began, everyone, Brazilian and Serbian alike, came together as part of one Island community, not by the power of sport but by the foolishness of an unwitting bar patron who had the audacity to change the channel.

Claudio Damascemo Facetimes with his family in Brazil. — Jeanna Shepard

Then it was game time.

“This is awesome, isn’t it!?” yelled John Mode, a teacher at the Tisbury School, as the ball dropped at midfield. “There’s such a good summer population for Serbia here and of course Brazil has a great year-round population.”

He was right. While Brazilians have had a strong presence of the Island for upwards of three decades and Portuguese has become the Island’s most widely-spoken second language, J-1 student visa programs have brought hundreds of summer workers from Eastern Europe to the Vineyard in recent years. Many of those workers are Serbian nationals. And on Wednesday they showed up in blue, white and red flag-draped droves to watch their team. What they lacked in numbers, they more than made up for in decibel levels.

“We love SEEEER-bi-A, we do. We love SEEEER-bi-a, we love you!” they sang. Other songs, one Serbian fan said, were probably best left untranslated.

“It was hard to compete with them,” confessed Gustavo Batista above the din. He moved to the Island from Brazil 16 years ago and now runs a construction company. He gave all his employees the day off to watch soccer. Most made it to Coop de Ville.

On Wednesday it was Brazil vs. Serbia — a battle for Vineyard bragging rights. — Jeanna Shepard

“I had no idea it would be like this, but it is crazy fun,” he said, an arm draped around his six-year-old son, Lucca. “I wish I could be in Russia right now, but this, it’s just as good.” He might as well have been standing at Estadio Maracana in Rio. Although rowdy soccer hordes aren’t best-suited for youngsters, Mr. Batista thought it was good preparation for his own first-grader. “He’s going to be the next big soccer star,” he said of his boy. “For the U.S.”

The patio wasn’t entirely divided. At least one yellow jersey could be seen floating through the ocean of Serbian flags. Kiria DaSilva, who moved to the Vineyard in 1999 from Rio de Janiero and attended elementary and high school on the Island, met her Serbian boyfriend, Nemo Bikic, while working at The Seafood Shanty last summer.

“I’m gonna sleep on the couch for the next two months,” Mr. Bikic deadpanned. For him, the Brazil-Serbia matchup wasn’t just personal, it was heaped with proud history. In 1930, at the first World Cup, Yugoslavia defeated Brazil 2-1 to move out of the group stage. More recently, the Serbian under-21 national team beat Brazil in an international friendly. “We have a small chance, but history has shown it is possible,” he said, in between gulps of beer and primal shrieks.

Ms. DaSilva wasn’t so sure. In fact she laughed at his assessment of Serbia’s chances. “I let them have their fun because I know Brazil will win,” she said. Ms. DaSilva was haunted by history of her own. In 2014, she looked on from the stands in Rio as Germany handed Brazil a crushing 7-1 defeat on their home turf. But this World Cup, Germany is already out. “That means we can win,” she said.

Thirty-five minutes into the game, Brazil fulfilled her prediction and scored on a breakaway that striker Paulinho flicked over the goalkeeper and into the net. Brazilian fans erupted, flicking whatever they could find — beer, mainly — in honor of his tally. They burst into their own song, “Se Eu Te Pego,” (in English “If I Catch You.”) Dejected Serbian fans stood nearby.

Joanne Andrade and son Jose embrace the victory by Brazil. — Jeanna Shepard

By halftime the Brazilians felt supremely confident. Mr. Rosa predicted a 3-nil victory for the Verde-Amarela, while Isadora Britu broke out her vuvuzelas, a plastic horn popularized in the 2010 South Africa World Cup. They blew to the rhythm of a ditty that lasted for the rest of the game. “Serbia ciaaaaao-aao, Serbia ciaaaaao-aao, Serbia ciao, ciao, ciao.” The Serbians, of course, didn’t go anywhere. They continued belting away, even as Ms. Britu yelled that they were singing to themselves. The Serbians didn’t seem to care at all.

After halftime, when Serbia squandered some fabulous chances at the net, Brazil came back and scored a second, decisive goal on a corner kick and accompanying header from Thiago Silva. Brazilian fans made sure Mr. Silva’s goal wasn’t the only header they got to see. Their reaction to the score was so intense that it knocked the television right onto bartender Ben Brittle’s head. Concussion protocol involved a Carlsberg taste test.

By the time the game was over, no one had left the patio. “That’s the beauty of the whole thing,” said Mr. Rosa. Coop de Ville owner Carroll (Petey) Berndt, agreed. He put steak tips on the menu for the Brazilians and ordered sausages for the Serbians, although they didn’t arrive in time.

“They all come together as friends,” he said.

And the 2-0 Brazil win aside, all left as friends too. Brazilian fans shook the hands of Serbians, just as the same gestures occurred between the players on the pitch.

For all their tough talk, Mr. Bikic and Ms. DaSilva were inseparable the entire match, holding hands through both agony and triumph. After they closed out their tab, Ms. DaSilva wasn’t so sure the couple would be able to maintain the rapport at home.

“I don’t know, it may be me who has to sleep on the couch,” she said.

More photos from the Brazil vs. Serbia match at Coop de Ville.