Streak snapped in Big D

In a game that could have gone either way, the shot Terry buried from 23 feet halted the momentum the Celtics had spent building in the second half. The 3-pointer wasn’t the winner in Dallas’s 89-87 victory last night, which halted the Celtics’ win streak at five. But it tied the score at 87, and gave Terry 17 points.

And when the Celtics thought about it, there was enough blame to go around.

“That was a huge play, and that was our defensive execution,’’ said coach Doc Rivers. “We had a breakdown — Ray had no choice, he had to do his job — but the breakdown is what caused the 3. But that happens.’’

Kevin Garnett pointed the finger at himself for not helping.

“I’ve got to show for [Rajon] Rondo,’’ Garnett said. “If I show, [Kidd] bugs out. Who knows what would have happened? But he found Jason Terry in the corner and he made a good shot.’’

Within seconds, Dirk Nowitzki would pull up over Glen Davis for a 16-footer, nailing what would be the decisive shot.

It was a play the Mavs ran all night for their star player, and when they needed a bucket, he cashed in. Nowitzki scored a game-high 25 points, dropping 16 in the second half, when he took advantage of a mismatch caused by nagging injuries. Jer maine O’Neal played 11 minutes in the first half, but his night was cut short by soreness in his left knee, leaving the 6-foot-9-inch Davis to do his best to stop Nowitzki, who at 7 feet could just shoot over him as he pleased.

“It was a good play, they ran it several times,’’ Rivers said. “Kevin switched on it, which left Baby on him. Ray was coming. He just didn’t get there quick enough. We wanted to get the ball out of his hands if we could have.’’

The Celtics saw their five-game winning streak go up in smoke not just because of late lapses, but because of a slow start. They missed 17 of their 25 first-quarter shots and let the Mavs pad the lead in the second quarter.

“You can’t spot a team points in the first quarter,’’ Garnett said. “You’ve got to come out more solid than that.’’