Carmelo Anthony scored 21 points .
The New York Knicks held on after blowing most of a 26 - point lead to beat the Boston Celtics 88 - 80 in Game 6 on Friday night and advance in the postseason for the first time since 2000 .
Carmelo Anthony scored 21 points and the New York Knicks held on after blowing most of a 26 - point lead to beat the Boston Celtics 88 - 80 in Game 6 on Friday night and advance in the postseason for the first time since 2000 .