OTTAWA -- The Montreal Canadiens learned their lesson about giving an opponent new life after blowing a four-goal lead against Calgary earlier in the week.
"We jumped out hard and then they started to turn it on pretty good towards the end of the first period," Price said. "As we started the second we knew we had to grab the momentum again and our guys popped in a couple quick and we just grabbed all the momentum after that. We definitely didn't want to give that one away. I think Calgary was a good learning lesson for us."
Chris Kelly scored for Ottawa, 0-4-1 in its last five.
"A couple of mistakes and it's 2-0 before we know it," Senators captain Daniel Alfredsson said. "We battled back hard in the first to get within one and take all the momentum back, but then whenever we have a lapse in our play it seems like it's costing us now, and they're very opportunistic on their chances."
Pouliot and Plekanec scored 1:52 apart to give the Canadiens an early 2-0 lead. Gionta made it 3-1 with his 16th early in the second. Pacioretty scored on a power play moments later to chase Mike Brodeur, who stopped 11 of 15 in his first start of the season.
"I'm a bit upset at myself with my performance," Brodeur said. "I had a chance to step in and play a lot better and I don't think I did that."
Plekanec beat Brian Elliott midway through the middle period for his second goal of the game, his 16th, tying Gionta for the team lead for the second time in the game. Kostitsyn made it 6-1 early in the third and Subban scored Montreal's second power-play goal later in the period.
Kelly scored midway through the first to draw Ottawa within 2-1. Elliott, who was replaced by Brodeur one night earlier, made 17 saves for the Senators.
Ottawa, which has lost six in a row at home, is last in the Northeast Division with 41 points.
"You can't go around feeling sorry for yourself," Alfredsson said. "We put ourselves in this position and we're going to keep working and trying to turn things around."
Pouliot scored his 10th goal when he beat Brodeur on a breakaway 1:53 in.
"If I would have come up with that save at the beginning it would have been a totally different start to the game," Brodeur said.
Plekanec made it 2-0 with his 15th at 3:45.
Kelly gave Ottawa some hope at 9:20 when he put Chris Campoli's pass home from the edge of the crease for his 10th goal.
Scott Gomez got the first of his two assists when he set up Gionta's goal 1:12 into the second.
Pacioretty, who was taken to hospital Tuesday night in Buffalo after he was struck in the chest by a puck, snapped a shot past Brodeur at 5:33 to make it 4-1.
"Everyone in this league plays hurt every night," said Pacioretty, who also assisted on Gionta's goal. "There's not much I have to say about that but you do what you can to help this team win games and I think tonight I did a pretty good job of that."
- Canadiens C Andreas Engqvist, who was called up from Hamilton of the AHL on Wednesday, made his NHL debut. RW Ryan White made his season debut after he was recalled from Hamilton on Thursday. White has two assists in 16 games with Montreal last season.
- Senators RW Alexei Kovalev returned after missing six games because of a knee injury.