BOSTON (AP) -- Ray Allen hit a go-ahead 3-pointer with 12 seconds left, Paul Pierce shut down Carmelo Anthony and the Boston Celtics rallied to beat the New York Knicks 87-85 in their playoff opener on Sunday night.
New York led 85-84 before Anthony was called for an offensive foul for pushing Pierce with 21 seconds remaining. Allen, who led the Celtics with 24 points, sank the decisive basket from beyond the left arc.
The Knicks then rushed downcourt and Anthony missed a long 3-point attempt with 2 seconds left. The superstar forward went 1 for 11 from the field in the second half.
Amare Stoudemire had 28 points and 11 rebounds for New York, and Anthony finished with 15.
Game 2 of the best-of-seven series is set for Tuesday night in Boston.
Pierce scored 18 points and Kevin Garnett added 15 points and 13 rebounds for Boston.
After Anthony's critical offensive foul, Rajon Rondo lined up to inbound the ball but called timeout. The next time, Allen inbounded from just in front of the half-court line on the right side. He threw the ball to Pierce, then circled to the other side of the court, caught Pierce's pass and fired up the deciding basket.
And when Anthony missed and the final seconds ticked away, Celtics coach Doc Rivers high-fived fans as he headed to the locker room.
Third-seeded Boston got a tough challenge from the Knicks, who allowed 105.7 points per game during the regular season, third-most in the league. Pierce was the defensive star for the Celtics, forcing Anthony to shoot with a hand in his face for much of the game.
With the score tied at 82, Toney Douglas hit a 3-pointer to put the Knicks in front with 38 seconds to go. The Celtics called timeout and immediately scored when Rondo tossed an alley-oop to Garnett on the inbounds pass.
The Celtics, who won their NBA-high 17th championship in 2008, are aiming to return to the finals after losing in seven games last year to the Los Angeles Lakers.
The Knicks, in the playoffs for the first time in seven years, have lost their last three postseason series and have gone 10 years without a win in a playoff game.
Boston trailed 51-39 at halftime but rallied to take a 66-64 lead early in the fourth. Stoudemire then scored 12 of the Knicks' next 18 points to power them to an 82-78 lead with 2:46 remaining.
Pierce followed with a 15-foot fallaway and Jermaine O'Neal scored on a putback, tying it with 1:12 to play.
It was a rough night for Anthony from the start. He picked up two quick fouls and went scoreless in the first quarter, but ended the half with 12 points.
New York put together a strong defensive effort in the second quarter, outscoring Boston 28-15. The Knicks scored the last six points of the first half on two free throws by Anthony, a powerful dunk by Stoudemire and two foul shots from Chauncey Billups.
The Celtics played without center Shaquille O'Neal, who also is expected to miss Game 2 with a sore right calf. O'Neal, a key to their interior defense, missed 27 games with a sore right leg. He returned on April 4 against Detroit, but quickly left again with the calf problem. He sat out the remaining six games of the regular season.
NOTES: During a timeout late in the second quarter, the crowd cheered when New England Patriots coach Bill Belichick was shown on the video scoreboard. He laughed and tipped his cap. But when the camera shifted to a spectator wearing a No. 1 Knicks jersey in the row behind him, the fans booed. ... The Knicks have lost their last three playoff series since beating the Miami Heat in seven games in the Eastern Conference semifinals in 2000.
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