Mathew Barzal had a goal and an assist, and Adam Pelech, Jordan Eberle, Jean-Gabriel Pageau, Anders Lee and Oliver Wahlstrom also scored to help the Islanders get their second straight win and improve to 6-0-1 at home. Semyon Varlamov stopped 34 shots.
New York, which got its highest scoring output of the season, beat Boston for the third time in three meetings — three of the Bruins' four regulation losses this season — to move one point behind Boston and Washington in the East.
“We understand how tough our division is top to bottom,” Lee said. “Boston's done a phenomenal job getting off to a good start and we're chasing them down. Any time you can close the gap a little bit, it's always a good evening.”
Nick Ritchie and Craig Smith also scored for Boston, which lost for the third time in four games. Jaroslav Halak had 30 saves in his first game against the Islanders since leaving after the 2017-18 season.
Beauvillier put the Islanders ahead at 5:41 of the third. Halak stopped Beauvillier's initial shot, then swooped in and took the puck away from Trent Frederic in front and backhanded it past Halak.
“Tie game going into the third period against arguably the best team in the league, that’s a good test for us,” Barzal said. “I thought we rose to the forefront today.”
Eberle made it 4-2 with 9:15 left, taking a pass from Barzal, going to his forehand to get Halak to go down before lifting the puck into the net.
Pageau scored on a short-handed breakaway with 7:36 remaining to give the Islanders a three-goal lead. Lee made it 6-2 with 5:16 left for his ninth, and Wahlstrom got his second with 3:27 to go.
“It’s a big win because we want to stay in the pack,” New York coach Barry Trotz said. “It’s just a big mess of teams that are very equal in terms of talent and in terms of the standings. It’s going to be a battle right to the end.”
Halak, who allowed the five goals on 18 shots in the third, had not given up a goal in the third period in six starts this season.
“Tonight was hopefully a one-off,” Ritchie said. “We just fell apart and kind of stopped playing, and that’s what happens in this league. There’s a lot of good teams.”
Varlamov made a nice save on a backhand try by Jake DeBrusk on a breakaway 7:21 into the second to preserve New York's 2-1 lead.
However, Smith tied it with 8:24 left in the second. On a Bruins rush, Smith sent the puck toward the net from the outside edge of the left circle with teammate Jack Studnicka charging toward the goal, but the it was deflected by the Islanders' Matt Martin up in the air and past Varlamov.
The Islanders were outshot 15-10 in the penalty-free opening period, but led 2-1 after 20 minutes.
Ritchie put the Bruins on the scoreboard 1:02 into the game, deflecting a pass by rookie defenseman Jakub Zboril past Varlamov for his seventh of the season.
Pelech tied it at 3:16, putting the puck in from the left side on a rebound for his first.
Barzal put the Islanders ahead with 7:21 left in the first period on a 2-on-1 with defenseman Nick Leddy for his seventh. Barzal had been held without a point the last four games after a career-high nine-game point streak. Leddy got his sixth assist in eight games, and Varlamov had his eighth career assist on the play.
Zboril returned to the lineup after missing the last two games due to an injury. Boston coach Bruce Cassidy said D Matt Grzelcyk skated in the morning but sat out against the Islanders. D Jeremy Lauzon is out four-to-six weeks with a broken hand. The Bruins were also without C David Krejci and D Kevan Miller.
Islanders forward Cal Clutterbuck did not play after the first period due to an undisclosed injury. Clutterbuck saw only 3:07 of ice time in the opening period. Trotz didn't have an update on Clutterbuck after the game, but said he wasn't ‘too concerned' about his status.
Bruins RW David Pastrnak played in his 400th career regular season game.
Cizikas’ assist on Pelech’s first-period goal was the 100th of his career.
GETTING READY FOR FANS
The Islanders plan to begin allowing fans at the Nassau Coliseum starting March 18 against Philadelphia. Fans will be limited to 10% of full capacity, which is 13,917. The Islanders will have about 1,000 healthcare workers in attendance for the previous game, on March 11 against New Jersey.
Bruins: At New York Rangers on Friday night to open a two-game series.
Islanders: Host Pittsburgh on Saturday night to open a back-to-back two-game series.