BOSTON — David Pastrnak scored twice, including his 40th goal of the season, for the Boston Bruins in a 3-1 win against the Ottawa Senators at TD Garden on Monday.

Charlie McAvoy had three assists, and Linus Ullmark made 30 saves for Boston (43-8-5), which has won four in a row.

“When [Pastrnak’s] really on like he was tonight, it jumps out at you,” Bruins coach Jim Montgomery said. “When he has his B-game, it still jumps out at you. That’s how good he is, and he was just ultracreative. I thought him and Charlie McAvoy were special tonight.”

Claude Giroux scored, and Kevin Mandolese made 29 saves in his second NHL start for Ottawa (27-25-4), which lost for the third time in 10 games (7-2-1).

The Senators won their previous two games against the Bruins this season (7-5 on Oct. 18; 3-2 in a shootout on Dec. 27).

“You’re never going to be satisfied, obviously, with a loss,” Ottawa defenseman Travis Hamonic said. “A tough back-to-back (after a 7-2 win against the St. Louis Blues on Sunday), really difficult building to come into historically no matter where that team is in the standings. They’re the No. 1 team in the League, so we feel like we played them really strong, obviously, all season, and it was a good game for us this afternoon, and just a couple chances end up going [in] the back of our net.”

Pastrnak put Boston in front 2-1 at 17:06 of the second period, scoring glove side from the bottom of the left circle off a pass from McAvoy.

Video: OTT@BOS: Pastrnak scores his 40th, 41st goal in win

David Krejci, who had the secondary assist on the play, was honored in a pregame ceremony for playing 1,000 NHL games, which he accomplished on Jan. 16.

“I knew what to expect a little bit, but it was more than I expected,” Krejci said. “It was a pretty special moment, having the family there with me. … Just a special moment and I’m very, very thankful that I’m part of this team.”

Pastrnak pushed it to 3-1 at 12:10 of the third period, shooting five-hole on a breakaway after receiving a stretch pass off the boards from McAvoy.

Pastrnak has 41 goals this season, trailing Edmonton Oilers forward Connor McDavid (42) for the NHL lead.

“It was a set play,” Pastrnak said. “[McAvoy and I] didn’t connect the tape-to-tape. He just let it bounce off the boards, and I told him right away, ‘That’s an unbelievable play.’ Heads down to him, great pass.”

The Senators were unable to score on a 5-on-3 power play for 1:49 after Bruins forward Craig Smith received a tripping penalty at 9:16 of the first period and Patrice Bergeron got called for hooking 11 seconds later.

“We would love to have that back in a tight game like this,” Ottawa coach D.J. Smith said. “But you can’t let it affect the rest of the game, which I didn’t think it did. I thought we played hard. That’s a really good team. We had our chances, I thought we checked really hard. [Mandolese] was really good. It’s just at the end of the day, a couple mistakes we made, you know, ended up in our net.”

Jake DeBrusk gave the Bruins a 1-0 lead at 15:09 of the first period, putting in the rebound of his own shot over Mandolese’s right shoulder. It was DeBrusk’s second goal in as many games after missing 17 games with hand and leg injuries.

“It’s obviously always a good time when you see the puck go in the net,” DeBrusk said. “To get us up in the first there, to get the first goal of the game, it’s always [nice getting] the crowd involved, and that’s what I wanted to do.”

Video: OTT@BOS: DeBrusk picks up his own rebound for goal

Giroux tied it 1-1 at 19:30 of the first. Bruins defenseman Matt Grzelcyk‘s pass attempt hit the skate of Senators forward Dylan Gambrell, who corralled the puck in the corner and centered it to Giroux in the slot.

“Just trying to work to get that puck back,” Gambrell said. “A couple of guys changing, and staying out there [for] the extra second just to keep them in their zone, but you know, it was a great finish.”

NOTES: Gambrell’s assist was his first of the season in his 36th game. … Pastrnak reached 40 goals for the third time in his NHL career (40 goals, 2021-22; 48 goals, 2019-20). Only four active players have more: Alex Ovechkin (12), Steven Stamkos (six), Auston Matthews (four) and Connor McDavid (four). … Boston has 91 points in 56 games, tying the NHL record for fewest games needed to reach 90 points in a season, previously set by the 1979-80 Philadelphia Flyers.