BOSTON (AP) -- Montreal kept up its strong play on the power play, against Boston and overall.
"It was a team effort tonight," Canadiens defenseman Roman Hamrlik said. "In the short term it's OK if two lines are scoring, but in the long term we need more. Tonight we had them all go."
Montreal improved to 5-0-2 over its last seven, and has beaten Boston eight straight and 15 of 18.
Montreal dominated the first period with four power-play opportunities and a pair of goals to take a 2-0 lead. After Plekanec opened the scoring, Maxim Lapierre scored 54 seconds later when he jammed home a rebound of Christopher Higgins' shot that squirted through the pads of Bruins goalie Tim Thomas with 8:30 remaining.
"They are a highly skilled hockey team and when they get a chance to showcase those skills, they do," Bruins coach Claude Julien said. "That is why they are the top power-play unit in the NHL."
The Canadiens went 2-for-6 on the power play and began the night with the top-ranked unit in the NHL.
Kovalev increased the lead to 3-0 when he scored the second power-play goal of the game, beating Thomas high on the glove side with 6:42 remaining in the second. Kovalev has eight points in the last five games.
Cristobal Huet made 23 saves for the Canadiens, who are unbeaten in their last four road games.
"They were very physical in the third, but Dandenault's first goal was huge and we regained the momentum," Huet said.
Montreal beat Boston for the fifth time this season and has outscored the Bruins 24-10.
Aaron Ward cut the lead to 3-1 when his slap shot from the blue line caromed off the boards and bounced in the net off the skate of goalie Cristobal Huet with 5:19 left in the second. Ward's goal snapped a scoreless drought of 115:41 for Boston.
Milan Lucic gave the Bruins a boost 2:01 into the third when he beat Huet to narrow the margin to 3-2, but Mathieu Dandenault responded with a pair of goals to ice the game for Montreal. Dandenault slid a soft backhander by Thomas with 8:04 to go in the third and added his second with 1:11 remaining.
"I just threw it on net and tried to keep it a bit off the ice," Lucic said. "I think our emotion was good but we didnt have a lot of control of that emotion."
Boston dropped to 3-7-1 in its last 11 games.
Ward returned to the Bruins' lineup after missing eight games with a broken foot. ... Montreal has outscored Boston 8-1 in the first period this season. ... Plekanec has eight points against Boston this season. ... Boston closed out its five-game homestand with a 3-2 record. ... Mark Streit added a pair of assists for Montreal. Dandenault had his first two goal game since Nov. 15, 2000.