Al Harrington scored 27 points and David Lee had 18 points and 18 rebounds for New York, which absorbed its third straight loss against one of the NBA's elite teams.
Allen took over in the fourth quarter of the tight, back-and-forth game. After Danilo Gallinari scored to give New York an 80-79 lead, Allen scored Boston's next 11 points. The All-Star guard's drive with about 6 minutes left put Boston in front 90-86.
Eddie House added a jumper and a 3-pointer from the corner to extend the Celtics' lead to nine with 4:05 to go. Chris Duhon responded with a three-point play for New York, but Garnett found Leon Powe inside for a dunk and Pierce hit a long jumper to make it 99-89 with 3:11 remaining.
It was a fitting end to a difficult week for the Knicks, who lost to three of the NBA's best teams and surrendered a couple of the greatest performances in Madison Square Garden history over a matter of days. Kobe Bryant scored 61 points in the Los Angeles Lakers' 126-117 victory Monday, and LeBron James had 52 points, 11 assists and nine rebounds to lead the Cleveland Cavaliers to a 107-102 win Wednesday.
The Knicks' "Dream Week" wasn't exactly a nightmare considering the competition, but it definitely was a restless couple of nights.
Powe had 13 points and Rajon Rondo added 12 for the Celtics, who made nine of their first 12 shots in the fourth quarter
- including 4-for-5 from 3-point range.
Kendrick Perkins' layup put Boston ahead 62-60 in the third, but Nate Robinson had a four-point play and Wilson Chandler had a terrific driving dunk to give the Knicks a four-point lead with 3 minutes left in the quarter.
Lee had 10 points in the third as New York carried a 76-72 lead into the final period.
Duhon had 15 points and seven assists, and Robinson finished with 13 points.
