BOSTON — Kyrie Irving knew Boston would be an unfriendly environment. It’s been that way for a few years now.

The TD Garden crowd serenaded the former Celtics guard with boos from the moment he touched the ball in warmups until he checked out for the final time with 5:17 left in the game. Celtics fans weren’t happy to see him and, based on Irving’s performance in the Mavericks' loss in Game 1 of the NBA Finals on Thursday, he wasn’t too happy out there, either.

“There were a lot of emotions going into it,” Irving said. “Just waiting for the opportunity to compete against a great Celtics team. We didn’t perform the way we wanted to tonight, and that starts with me … gotta take some accountability.

“It’s not the first time I lost in Boston.”

Irving managed 12 points on 6-of-19 shooting to go with three turnovers. He missed all five of his 3-point attempts as the Celtics rolled to a decisive 107-89 victory. Irving has lost each of his last 11 games against Boston dating to his time with the Brooklyn Nets in 2022.

“For Boston, you are the villain,” Luis Belacques, 25, of Montreal, said of Irving before attending the game. “That mark will be left forever.”

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Irving and the Celtics have a tumultuous history. He flipped on a verbal commitment to extend his time playing in Boston and miffed Celtics fans on numerous occasions after departing — including stomping on the center-court logo, burning sage on the parquet before a game and making obscene gestures to fans. Irving also has alleged “subtle racism” in terms of comments he has received from patrons at TD Garden.

The eight-time NBA All-Star seems to have reinvented himself in Dallas, but Boston could care less. It’s a fanbase that loves a villain — and it’s a role Irving seems likely to play for a long time.

“I hope he gets booed. Like, crazy booed,” Josh Ouellette, of Caribou, Maine, said outside TD Garden before tip. “It’s what he deserves.”

The Game 1 struggles were a surprise for a proven playoff performer like Irving. A 2016 NBA champion, Irving has averaged more than 23 points per game on 46% shooting in his playoffs career dating to 2019. He has only shot lower than Thursday’s 32% field-goal percentage twice in postseason games since 2019.

“It’s basketball at the end of the day,” Irving said. “I’m used to (the environment in Boston) at this point. I’m expecting the same things in Game 2, with the crowd trying to take me out of my element. I have to stay poised and stay confident.”

Of course, it wasn’t just Irving who struggled Thursday. The Mavericks’ 89-point output was their lowest of the playoffs. The Celtics had as many blocks in the game as the Mavericks had assists. Luka Doncic, playing in his first NBA Finals game, committed four turnovers despite a game-high 30 points.

“It’s not the booing, it’s not the missed shots,” Irving said. “It’s more or less our attitude and how we approach things possession by possession. I haven’t had the best games offensively this playoff run … but now it’s our turn to go through it together.”

Follow Richard Morin on social media @ByRichardMorin