Kevin Garnett scored 26 points and had 10 rebounds, Rajon Rondo recorded 21 points and 12 assists and the veteran Celtics completed their 4-0 best-of-seven rout over the Knicks.
Meanwhile, the second seed Miami Heat had their series advantage cut to 3-1, while the Atlanta Hawks took a 3-1 series lead over Orlando and the New Orleans Hornets leveled their match-up at 2-2 with the Los Angeles Lakers.
Having reached the NBA Finals in two of the last three seasons, Boston produced a business-like win as they nearly led from start to finish.
The revamped Knicks, who signed All Star Amar’e Stoudemire in the off-season and traded for All Star Carmelo Anthony at mid-season, suffered a disappointing exit from the playoffs.
“They’re going to be good,” Boston coach Doc Rivers said of the Knicks. “They’re just going to be able to keep building. As long as everyone stays patient with them, it will work out.”
Anthony finished with 32 points and nine rebounds and New York got 19 and 12 rebounds from Stoudemire who was limited in the series by back spasms that nagged him since Game Two.
Knicks starting point guard Chauncey Billups also injured his knee in Game Two and was sidelined for the rest of the series.
Miami attempted to punch its ticket to the second round but was stalled by Philadelphia 76ers who pulled off a gritty 86-82 win to avoid a first round sweep.
Philadelphia’s Lou Williams had 17 and made the go-ahead three-pointer with eight seconds for the winning margin while LeBron James scored 31 and Dwyane Wade had 22 for the Heat.
Game Five is Wednesday in Miami.
In New Orleans, Jarrett Jack made a clutch jumper to put the home team up four with nine seconds left, and Chris Paul had a triple-double of 27 points, 15 assists and 13 rebounds as the Hornets outlasted the Lakers in a 93-88 win.
Kobe Bryant, who exchanged words with Paul throughout the testy affair, shook off a slow start and a sore ankle to finish with 17 points and eight assists.
Los Angeles stayed close but never led in the second half and will try to regain control of the series in Game Five on Tuesday in Los Angeles.
Atlanta led Orlando by as much as 16 in the second quarter, but still had to hold on late to fend off the Magic in an 88-85 win.
Orlando forward Hedo Turkoglu missed a three-pointer attempt at the buzzer to seal his team’s fate as the Magic wasted Dwight Howard’s dominance of 29 points and 17 rebounds.
Jamal Crawford had 25 points off the bench to lead the Hawks who will try to close the series in Game Five on Tuesday.
