Doc Rivers was furious, livid, outraged at the officiating in the Celtics’ 87-71 loss to the Knicks Tuesday night in Game 2 of their first-round playoff series.

Specifically, Rivers was angry at the foul calls against Kevin Garnett, who scored 12 points and grabbed 11 rebounds but was saddled with foul trouble from the start. He picked up two fouls in the first quarter and ended up playing 24 minutes.

“Listen, I thought the fouls on Kevin, first of all they were horrendous,” Rivers said after the Celtics fell in to a 2-0 hole in the best-of-seven series that shifts to Boston for Game 3 Friday.

“And secondly, I thought they had a huge effect on us,” Rivers continued. “Kevin had three fouls that . . . I was . . . I mean, him not being on the floor, playing 24 minutes and never getting your rhythm, where you could see, it looked like he was going to have a game, it hurt us.

“That’s just the way it goes. There’s nothing I can do about it now. I thought if it could’ve gone either way on three of those, they all went against Kevin. I think that’s tough.”

Garnett was a key part of the Celtics’ plans coming into the game. They wanted to establish him early, unlike in Game 1. Garnett did make the Celtics’ first shot, but he picked up two quick fouls and had three by halftime.

He picked up another foul in the third quarter, after which he slammed the ball to the court several times out of frustration.

“At times, it’s frustrating, but fouls are part of the game,” Garnett said. “Refs are calling things but it’s an aggressive time in postseason play. I just have to be consistent and position myself not to foul so much.”

The Celtics were not the same with Garnett having to play tentative.

“Everything we do surrounds getting the ball to Kevin inside and working from there,” Paul Pierce said. “When he gets into foul trouble we have to find ways to make adjustments, giving other people a chance to step up. When he’s not in the game we really don’t have an inside presence.”

Said Jason Terry of the impact of Garnett being in foul trouble, “Oh, tremendous, tremendous. He’s a big presence for us and he was not able to be aggressive like he wanted to, picking up those early fouls.”

Brandon Bass had a different take.

“You know, it didn’t really affect us,” Bass said. “When someone gets into foul trouble or someone goes down, guys have to step up.”