Finishing off a back-to-back in Montreal on Thursday night, the Black and Gold fell to the Habs 6-4 in their rival's home opener.
The Bruins are now 1-1 on their three game road trip that ends in Buffalo on Saturday, and 2-4-0 on the season.
Boston overcame a 2-1 deficit to lead 3-2 late in the second period, but the game tipped in the Canadiens' favor with tough bounces and poor defensive breakdowns on the Bruins' part.
Montreal led 4-3 heading to the final 20 minutes, and sealed their 6-4 win late in the third.
"I don't know, I've got to do something about it," Rask said with a sigh postgame in Montreal, of his troubles against the Habs. "You know, I don't know, I'll figure something out."
"We started good, I felt good in the first and then you get that one bounce, 'OK, we'll battle through it.' Then you get another one and you're like 'OK, doesn't matter,' and then you get a third one, and then you're kind of like 'OK, it's one of those nights again', so it's just - I've got no answer."
"If I had an answer, we'd probably win more games here, but you know, we'll battle. We'll keep battling and we'll be stronger."
Despite the mistakes, the Bruins kept up their effort.
They came out strong in the first period, outshooting Montreal 13-7. They had three power plays, with Zdeno Chara cashing in by tipping a one-timer from David Krejci past Carey Price to put Boston up 1-0.
Patrice Bergeron had two chances point-blank, but was robbed by Price.
Max Pacioretty added his own power play goal in the first to tie the game at 1-1, after David Desharnais split the Bruins' defense. Rask made the initial stop, but bodies crashing the net knocked it in.
A five-goal second period saw momentum swing back and forth between the sides.
Rask had to come up with big saves off odd-man rushes early in the second to keep it a tie game.
When Montreal broke through with a Brendan Gallagher tally to go up 2-1, Carl Soderberg responded just 51 seconds later.
The line of Soderberg, Chris Kelly and Loui Eriksson has consistently been a strong trio for the Bruins, and proved that again with two goals in a span of 1:57 to put Boston back on top, 3-2.
Eriksson scored the go-ahead when Torey Krug perfectly placed a shot pass to the winger planted in the blue paint.
It marked the first time Boston had scored more than two goals in a game all season.
"Well, it was better, definitely better, and you could see it coming last game," Julien said of the team's offense. "I think we had about 26 scoring chances in Detroit and only scored two. We're starting to score some goals; we've just got to clean up our end a little bit more."
The Bruins looked in control as the second period was winding down. They had battled back, and
The Habs then scored two goals 1:25 apart to take a 4-3 lead entering the final frame. On the tying goal, Rask was taken out of the play when Rene Bourque knocked Dennis Seidenberg into him. Jiri Sekac saw Rask down and put home the loose puck.
A minute and a half later, P-A Parenteau found himself all alone and beat Rask down low past his right skate.
"Yeah, everything was under control and then just a couple breakdowns and it' a 4-3 game, so it obviously kind of shakes you a little bit," said Rask. "But then again, we wanted to come out strong in the third and shake those off but the start in the third wasn't the sharpest and then they get that goal and that was it."
Montreal scored 7:17 into the third, with Gallagher getting a stick on a double-tip past Rask to make it 5-3.
"Some costly mistakes and things that we had talked about and shown before the game, and I think we lost our focus and because of that, we made some real bad mistakes and they ended up in the back of our net," said Julien.
"So as a coach, you're happy with the effort because it was there, but disappointed in some of the decisions that we made that cost us some goals, so we've got to fix that."
"But as long as the effort is there, you've got an opportunity and you've got a chance, so we're going to try and fine-tune our game."
Allowing five goals is not the Bruins' forte, let alone six. The fifth causes an end to Rask's night, with Niklas Svedberg taking over.
Rask finished with five goals allowed on 23 shots, and was serenaded by the crowd with "Tuu-kka" chants. Svedberg made two stops in the final half of the third period.
"I think at that point, you're looking for something to spark your team and maybe slow things down a little bit too before the next faceoff, so I made that change," said Julien. "But it's just one of those games, where a lot of bouncing pucks here and there, and first goal, we put it in ourselves and that's just an example but, again, it's a team thing right now."
"There's a lot of mistakes made in front of him so again, I'm not going to start pointing fingers at one person or one player - I'm going to look at our whole team and as a team, we made too many mistakes here."
Simon Gagne narrowed the score to 5-4 with 5:49 left in the third, when a Lucic shot went off his leg while crashing the net. It was reviewed for a "distinct kicking motion," but stood as a good goal.
The Bruins' chance at a 6-on-5 situation was halted by Lucic being called for boarding after laying a hard hit on Alexei Emelin.
Boston still put out and extra attacker to make it 5-on-5. Montreal's sixth goal came with an empty-netter on the power play in the final 20 seconds.
With the Bruins starting to find their offense, they preached getting their team defense in line, and eliminating those costly defensive breakdowns and coverage issues.
"I think a lot of it is just mental, you know. In these games, we don't give up a lot of shots, but when we do, they're tough shots and they're scoring chances," said Rask.
"That's not us," said Krug, of the defensive lapses. "We're a team that prides ourselves on our defense and when we're spaced out in our defensive zone, bad things are going to happen."
"We didn't collapse in front of the net like we normally do and shame on us for that, so we're going to get back to our defensive ways next game."
The Bruins will not practice on Friday in Buffalo after the back-to-back, resting up before ending their road trip against the Sabres on Saturday night.
"It's not alarming. It's more about, we've got to correct those things," said Julien. "There's nothing alarming. These guys have been a lot better defensively than we've seen, so it's not like we've got a bunch of new guys that don't know how to play."
"It's more of we've got to be a little bit more committed to playing good defense and good defense wins games and championships, so we've got to be more committed in that area."
"I think it goes for everybody," said Bergeron. "We just need to be smarter defensively in our zone."