Did someone tell James Harden that the Met Gala was in Boston?

The Sixers guard was all business after dropping 45 points in Philadelphia’s 119-115 win over the Celtics to take Game 1 of the Eastern Conference semifinals, which coincided with Met Gala Monday.

But, he also turned heads in the back hallways of TD Garden with an eccentric ensemble.

The former MVP sported a multi-colored fur jacket and oversized matching pants as he made his way to the locker room before tipoff.

Harden was all smiles with his hands in his pockets while cameras captured his pregame fit — which also included a neon yellow design and leather fabric on his zip-up jacket.

Meanwhile, other athletes — including Patrick Mahomes and his wife, Brittany Matthews, Clippers guard Russell Westbrook and Heat legend Dwyane Wade and his wife, actress Gabrielle Union — were posing on the Met Gala red carpet in New York City.

After the Game 1 win — without star center Joel Embiid due to a knee injury sustained in Round 1 — Harden was still locked in.

The future Hall of Famer can be seen yelling at his teammates to forgo celebrating and head to the locker room in post-game videos on social media.

“It’s one game, bro! It’s one game!” Harden can be heard telling his teammates: Forwards Tobias Harris and Paul Reed, and guard Shake Milton, who were talking together on the court.

Harden — who silenced critics questioning if he can still carry a team — propelled the Sixers to a 1-0 lead in the series against the title favorites on their home floor in Boston.

With seconds to go in the fourth quarter and the Sixers trailing by one, Harden drained a step-back 3-point jumper over Celtics veteran Al Horford to give the 76ers the lead for good.

Harden tied his playoff career high of 45 points on 17-of-30 from the field, six assists and just three turnovers.

The Sixers took home court advantage with the win. The hope is Embiid is able to return for Game 2.

“I haven’t felt one of those zones in a minute,” Harden said with a smile after the game. “You know what I mean? Just to be aggressive and shoot the basketball and do what I want. That felt really good. … I’m capable of doing it, so it felt good. It felt good to make those shots, to give ourselves a chance.”

Sixers head coach Doc Rivers said he believed Harden had the “perfect mindset” in Game 1.

“The guy is a Hall of Famer, and all you hear is the other stuff about him,” Rivers said. “And he was fantastic.”

Philadelphia is riding high after a Game 4 win over the Brooklyn Nets to close out a first-round sweep last month.

Game 2 of the second-round series between the Sixers and Celtics is set for Wednesday in Boston.