"We needed to create more scoring chances because we didn't have many in the first two periods, so we tweaked the lines a bit and the guys responded well," Julien said. The Bruins improved to 7-1-1 and maintained their hold on first place in the Northeast Division.
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"That Krejci line's been awesome for us but (Wednesday) they weren't able to generate much, so I said, 'Let's move guys around here and give them a little spark,' and it worked out," Julien said. "Look at Siggy driving the net on that first goal."
Seguin sneaked in front to take a pass from Krejci and lift it over Carey Price to tie the game only 14 seconds into the third period.
The speedy young center then slipped the puck to the left wing on a rush, and Lucic fed it in front. The onrushing Krejci got there just before Montreal center Tomas Plekanec and tipped it in at 2:05.
P.K. Subban scored his first goal of the season on a second-period power play for Montreal, which was shut down by Tuukka Rask while outshooting Boston 11-4 in the first.
The Canadiens (6-3-0) had their five-game home winning streak was snapped.
"We played well in the first period, but starting in the second, we kind of backed up," said defenseman Andrei Markov, who picked up his ninth point in nine games. "We stopped playing our game."
Boston outshot Montreal 23-22.
The Canadiens play Thursday night in Buffalo before facing the Toronto Maple Leafs on Saturday night at the Bell Centre.
Julien called it the best game so far this season for Rask, who has built a 6-1-1 record as the starter while veteran Tim Thomas is on a self-assigned sabbatical.
Rask stopped Lars Eller on a breakaway 10 minutes into the game, and got a break in the second when Plekanec was in alone but lost control of the puck and shot it into the corner rather than at the net.
"He's had the right attitude," Julien said of his goaltender. "With the high expectations, he's just doing his job.
"He's a normal goaltender, which might be a surprise to a lot of people," he said. "But he's so easy going. There are no issues."
The Krejci, Lucic and Nathan Horton line has been Boston's best this season while Seguin went into the game in a slump with only one goal in the first eight games.
"I was feeling snake bitten, but I'm glad one went in and we pulled this one out," Seguin said. "I feel I've been playing decently.
"I had a couple of goals called back. Things weren't going in. But we got it going in the third," he added.
The Canadiens did not allow the Bruins a shot on goal until the game was more than 11 minutes in, but solid saves from Rask kept it scoreless.
Subban broke the deadlock at 10:53 of the second with Lucic serving a high-sticking penalty.
The flamboyant defenseman took a pass from Markov, and saw his point shot go off Rich Peverley's stick and past Rask. It was Subban's first goal and third point in three games since he ended a holdout by signing a two-year contract.
The goal drew big applause from the Bell Centre crowd as Subban did the leg-lifted "Joel" pose in celebration.
It ended Boston's string of 16 straight penalty kills to start the season.
Price left the ice in a hurry during pregame warm-ups after he was hit in the groin area by Lars Eller's shot, but was OK to play. ... Prospect Blake Geoffrion, who fractured his skull in an AHL game at the Bell Centre during the lockout, says he feels better and will be examined by a doctor in Montreal on Thursday to see when he can resume training. ... Montreal scratched Tomas Kaberle, Ryan White and Yannick Weber. ... Boston was without Brad Marchand, Shawn Thornton and Daniel Paille because of injuries.
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MONTREAL, CANADA - FEBRUARY 6: P.K. Subban #76 of the Montreal Canadiens poses for his official headshot for the...