EAST RUTHERFORD, N.J. ? There was frustration and anger in Jim O’Brien’s voice as the Boston coach spoke Tuesday about the Celtics’ loss in Game 1 of the Eastern Conference semifinals.

New Jersey, the team that beat the Celtics in the conference finals a year ago, was there for the taking Monday night.

Turnovers, missed shots, foul problems — all the things the Celtics needed New Jersey to do wrong in the opener of the best-of-seven series happened, and Boston couldn’t take advantage in a 97-93 loss.

“I feel the same as last night,” O’Brien said before the Celtics practiced at Seton Hall University in South Orange. “We’re all angry we lost the game.”

O’Brien’s frustration showed when asked about the Nets’ fastbreak, the one thing that makes Jason Kidd and New Jersey tick.

“They didn’t play well and we didn’t play well,” O’Brien said. “It came down to us stopping them in transition. That was our No. 1 goal and we did not get the job done. You don’t deserve to win when you do that.”

New Jersey outscored the Celtics 23-5 on the fastbreak and outrebounded them 44-30.

Still, Boston had chances in the final minutes.

Antoine Walker, Tony Delk and Paul Pierce, a Kansas University product, missed three-pointers that could have tied the game or put Boston ahead.

“We felt like we let that game slip away,” Pierce said a little more than 12 hours after scoring 34 points but missing a game-tying shot with fewer than 10 seconds to play. “We’re all disappointed in the loss, that’s natural.

“If you’re not disappointed then you shouldn’t be here. Everybody should be (angry) and ready to do something in Game 2.”

The Celtics will get that chance tonight at Continental Airlines Arena.