Brad Marchand had a goal and an assist to extend his point streak to 12 games, and David Pastrnak had a goal and two assists to stretch his point streak to 11 games for the Bruins (10-1-2), who have won five in a row and are 7-0-2 in their past nine.
Patrice Bergeron had a goal and an assist, and Tuukka Rask made 30 saves.
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Marchand has 23 points (eight goals, 15 assists) during his streak; Pastrnak has 27 points (13 goals, 14 assists) during his run.
"A lot of that comes … we are playing well as a team and that always helps, and that's a huge pickup," Pastrnak said. "We're all doing well and playing with a lot of confidence, so obviously that helps. But yeah, we're winning, and that's the major thing."
Video: OTT@BOS: Pastrnak sets up Marchand on power play
Anthony Duclair and Connor Brown scored, and Craig Anderson made 27 saves for the Senators (3-8-1), who are 0-4-1 on the road.
The game was tied 2-2 entering the third period.
"You know what, I think it's a good learning lesson for us," Ottawa coach D.J. Smith said. "You've got to stay with the plan, you've got to stay [with it] when you're playing a team as good as these guys. I thought we made two mistakes tonight and they end up in the net. …
"But I really did like our effort for a lot of the game. This is one of the best, if not the best team in the League, and I thought we stayed with them."
Video: OTT@BOS: Pastrnak sets up Bergeron in front
Pastrnak gave Boston a 1-0 lead on the power play at 1:17 of the first period. Bruins defenseman Torey Krug shot the puck into the offensive zone from his own end, and Pastrnak won a race to the puck before taking it to the net and scoring.
Senators forward Scott Sabourin left the ice on a stretcher at 3:08 after a collision with Bruins forward David Backes.
Their heads appeared to make contact, and Sabourin remained on the ice for more than 11 minutes while he was attended to before being wheeled off. He was hospitalized overnight, and the Senators said he was conscious and speaking.
Backes left the game following the collision with an upper-body injury.
"Yeah, it was tough to get her going after you see [Sabourin] on the ice. It was pretty emotional for all of us," Ottawa defenseman Mark Borowiecki said. "That was one of the first ones, I think for me personally, I've ever been a little choked up. I love that guy. We all love him in here. He's a team-first guy, would do anything for anyone, and to see him down there like that, we were all pretty shook up."
Duclair tied it 1-1 at 12:04.
Video: OTT@BOS: Duclair goes top shelf off Brown's dish
Bergeron gave the Bruins a 2-1 lead at 1:51, but Brown tied it 2-2 at 3:04.
With the Bruins already killing a minor penalty for too many men on the ice, Marchand was called for a hooking minor and a double minor for spearing at 6:08. The Bruins killed 55 seconds of a 5-on-3 and then 1:05 more of an Ottawa 5-on-4.
"For sure, it definitely helped us," Bergeron said. "And they got some good looks, Tuukka made some great saves, but at the same time, I thought we did a good job overall and yeah, you often say that power play or penalty kill, special teams can give you some momentum, and I thought tonight it was the penalty kill that did it."
Danton Heinen put the Bruins ahead 3-2 at 5:43 of the third period, and Marchand made it 4-2 with a power-play goal at 6:50.
Jake DeBrusk made it 5-2 with 3:44 left.
Video: OTT@BOS: Heinen cuts to the front to put Bruins ahead
They said it
"I don't think there is anything you can say, you just have to play the game and play it hard and hope for the best. They just wanted to know that he was moving, and I think that made them feel better." -- Senators coach D.J. Smith on his team reengaging after the Scott Sabourin injury
"He is on another level right now. His ability to make plays … both his pass to [Bergeron] on the second goal and his pass to me on the third, he's just seeing things that other guys just could never see." -- Bruins forward Brad Marchand on linemate David Pastrnak
Need to know
The Senators were without forward Logan Brown (upper body) after the first period. … Bergeron got his 500th NHL assist on Marchand's goal. … Boston has won nine straight games against Ottawa in the regular season; the Senators' last win came March 21, 2017, at Boston. … The Bruins reached 10 wins in 13 games or fewer for the fourth time. They also did it in 1929-30 (10-2-0), 1938-39 (10-2 with one tie) and 1976-77 (10-3-0). ... Ottawa was playing its first game in six days.
Senators: At the New York Rangers on Monday (7 p.m. ET; MSG, TSN5, RDS, NHL.TV)
Bruins: Host the Pittsburgh Penguins on Monday (7 p.m. ET; NHLN, SNE, SNO, SNP, TVAS, NESN, ATTSN-PT, NHL.TV)
Video: Pastrnak and Heinen power Bruins past Senators, 5-2