"Tuukka, you can usually tell how calm and composed he looks and it means we're generally calm and composed in front of him," Bruins coach Bruce Cassidy said. "We're getting the result for him playing in front of him."
Rask earned his fourth straight win after struggling to a 3-8-2 start this season, which prompted many Bruins fans to call for Cassidy to play backup Anton Khudobin as the No. 1 goalie. Khudobin opened the season 7-0-2.
"We're trying to build an identity that you have to battle hard and you have to skate hard," Rask said. "From that, you kind of build that identity and reputation to be a hard team to play against. That's something we want to accomplish and need to accomplish to make the playoffs and be an elite team in the league. I think we're heading in that direction."
The Bruins limited New York's chances most of the game.
"That's what they do," Islanders coach Doug Weight said. "They have big, long (defenseman), protect lanes and protect the net."
Marchand's goal made it 1-0 at 10:51 of the second period. With the Islanders short-handed because of a too-many-men-on-the-ice penalty, Marchand took a pass from Krug, broke in down the left wing and snapped off a wrist shot that slipped between Halak's pads.
Early in the third, Marchand was given a five-minute major for interference when he came charging across the ice to hit John Tavares near the boards, but New York's Ryan Pulock took a cross-checking penalty when play stopped.
Boston's David Backes also got a major -- for head-butting -- and a game misconduct later in the third.
DeBrusk made it 2-0 when he collected a loose puck in the slot, spun and beat Halak with a wrister inside the right post 6:45 into the third.
Lee scored on a redirected shot from the top of the crease with 3:08 to play, just after Backes' penalty expired.
Heinen sealed it with 42 seconds left.
Rask was hardly tested through the first two periods, but made a solid glove stop on Mathew Barzal's shot from the left circle late in the second.
"We didn't enter the zone like we normally do tonight," Lee said. "We came in with no speed."
The best chances of a scoreless first came when Backes had a pair of bids from the edge of the crease seconds apart. Halak flashed his left pad to stop both.
Both teams seemed focused on limiting quality scoring chances from the start of the game -- and they did that, relying on tight checking and solid positioning to block shots and limit shooting angles in the first two periods.
Islanders D Johnny Boychuk missed his second straight game with a lower-body injury. ... Bruins C Noel Acciari was out with an upper-body injury and forward Matt Beleskey was a healthy scratch. ... Boston C David Krejci took a puck in the mouth midway through the first and headed to the locker room, but returned about four minutes later. ... Barzal entered leading NHL rookies with 27 points. ... It was the first of three games between the teams this season, and the only one in Boston.
Islanders: Host the Capitals on Monday. New York lost 4-3 on Nov. 2 at Washington in their first meeting.
Bruins: At the Detroit Red Wings on Wednesday in the first game between the teams this season.
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