Boston Celtics' Paul Pierce (R) drives into the defense of New York Knicks' Carmelo Anthony during the first half of their NBA basketball game in New York March 21, 2011. Knicks' Chauncey Billups is at left (4) REUTERS

NEW YORK, March 21 - Boston gave New York Knicks fans further reason to grumble on Monday after the Celtics produced a stunning fourth-quarter run to claim a 96-86 victory.

Paul Pierce scored 21 points, including nine straight Boston points during a critical stretch in the fourth quarter, while Kevin Garnett recorded 24 points and 11 rebounds to help the Celtics (50-19) overcome a nine-point deficit in the final quarter.

For New York, the loss intensifies the scrutiny of a team that has gone just 7-9 since a blockbuster trade that landed Carmelo Anthony and Chauncey Billups.

"We have to figure something out. It's not real good right now, obviously," New York coach Mike D'Antoni told reporters after the Knicks (35-35) third straight loss and sixth in seven games.

"A lot of times I have my idea of how I want us to play. If we can't do that then we have to play some other way."

Their recent rough patch has seen team captain Amar'e Stoudemire publicly implore his team to follow coach D'Antoni's system, while newcomer Anthony has said it will require patience as the squad develops chemistry.

Anthony scored 17 of his 22 points in the first half on Monday as the Knicks built a 14-point halftime lead, but he and Stoudemire failed to record a field goal in the fourth.

New York held an 82-73 advantage with 7:26 remaining before Boston ran off a 13-0 run marked by Pierce's hot stretch, and ended the contest with 10 consecutive points to put the Knicks away.

The victory helped the Celtics stay tied with the Chicago Bulls at the top of the Eastern Conference.

Ray Allen had 15 points for Boston but needed stitches to close a cut over his eye after he was struck by an elbow that briefly sidelined him in the third.

Anthony also suffered a cut near his eye when he collided with a player while chasing a loose ball late in the fourth.

Billups finished with 21 and Stoudemire tallied 16 and 11 rebounds in the losing effort.