The Wizards’ Thomas Bryant goes up for what would ultimately be ruled the winning basket as the Knicks’ Allonzo Trier, right, comes over late and blocks the shot while Emmanuel Mudiay defends. Trier was called for goaltending on the play. (Andrew Boyers/Action Images Via Reuters)

In the final 3.3 seconds of this unfamiliar game, the fans who filled every seat of O2 Arena were on their feet. They needed a better view of the “home” team, the Washington Wizards, as the final play unfolded. When Wizards center Thomas Bryant went for a layup over two New York Knicks players, the ball did not go through the cylinder. Yet those home team players ran and leaped and celebrated with hugs and high-fives even though Knicks guard Allonzo Trier had blocked the shot.

Paying customers such as Irish-born Patrick McCarthy looked on in amazement, confused about this game the Americans play. For the unfamiliar, the goaltending call on Trier, upheld following a lengthy officials’ review on courtside replay monitors, sealed a 101-100 Wizards win.

But for McCarthy and his three friends watching from the stands — making up something of a small U.N. contingent — the ending had at least some of them baffled.

Adam Schwartz, the Australian, knew “the thing got rejected.”

Ethan Roberts, the American from Boston, knew the call was “goaltending.”

Vytas Macenas, the Lithuanian, knew “it was all legit, the ball was going down.”

But McCarthy?

“I’ve got no idea, but I’m having a good time,” he said.

The NBA has played a game in London for nearly a decade, and a culturally diverse and international crowd — along with a sizable amount of converts — behaved like basketball fans Thursday.

They cheered at the appropriate times and reacted as if rookie Troy Brown Jr. had invented fire when he dunked over Knicks guard Frank Ntilikina in the third quarter. They remained in their seats as the home team completed its 19-point comeback — in the fourth quarter, the concourse was virtually empty save for arena workers and some rushing back into the arena. They clapped on beat when Europe’s “The Final Countdown” blasted in the arena as the Wizards walked onto the court for their game-winning play. They appreciated the game.

“The atmosphere was amazing,” Bryant said. “The atmosphere was absolutely crazy out there. These people didn’t cheer for just a team. They just enjoyed basketball.

“They didn’t take it for granted at all, so I really appreciate the fans out here.”

The 20,000-seat venue was at capacity, with many who at best could be described as basketball neophytes and Britons who came just to see a spectacle.

“I’m not an NBA fan, but it’s a really big event at the O2, and also the NBA puts on so many halftime, court-time shows, which makes it fun. American sports are fun,” said James Macfarlane, who only stepped outside into the concourse for a vape break. “Compared to [soccer] and all the other U.K. sports, America really knows how to entertain fans in between.”

Macfarlane said his favorite part of the game came when English comedian Michael McIntyre shot baskets at halftime. David Jarvis, who came with Macfarlane, had never attended a basketball game. Now he and Macfarlane plan to travel to Charlotte for the 2019 All-Star Game.

“The extravaganza. To me, it’s like a show,” Macfarlane said. “I mean, there’s so much more than just the game. It’s the feeling. It’s the vibe. Come on, it’s like literally the circus has come to town.”

While the pair of British gentlemen, dressed bespoke in suits, celebrated the spectacle, Azerallee Brown writhed in agony.

“What the f---!” she yelled at a monitor as the Knicks couldn’t score on a fourth-quarter possession.

Brown won two tickets to the game, and her passion traveled across the Atlantic from her home in the Bronx. She wore a John Starks jersey and long-sleeve Knicks shirt that covered her Knicks tattoo on her forearm, as well as a “Make The Knicks Great Again” hat and team logo gold chain around her neck.

Brown’s deep love for the Knicks made her feel like a stranger in this arena and this country.

“I noticed that they aren’t really basketball fans out here,” Brown observed. “There was a gentleman, he was with his son. The son had full Knicks gear on.”

Brown asked the son who was his favorite player and was met with a blank stare.

“This must be an event for them,” she said. “Londoners aren’t really basketball fans.”

The dramatic finish might have ruined Brown’s night after the goaltending call gave the Wizards a rousing win. Though some in attendance might not have known what happened, the game created at least one new fan.

“I have no idea, but I love the American razzmatazz,” McCarthy said, weighing the game’s finish vs. being entertained. “It’s brilliant.”