TORONTO - For the second straight game, the Bruins found themselves in an early hole.
An already boisterous Air Canada Centre - riding high from Toronto's ceremony to kick off its 100th Anniversary season- kept the energy going when Connor Brown scored just over two minutes into the opening frame en route to an eventual 4-1 win.
The Leafs' early lead quickly became a 3-0 deficit for the Bruins seven minutes into the first period.
David Pastrnak scored on a power play for his third of the season to make it a two-goal game at the end of the period, but the Black & Gold couldn't turn on the jets.
The Bruins were able to come from behind two nights prior and score five unanswered goals en route to a 6-3 win in Columbus, but they know that's not the ideal formula for earning victories.
"I don't think we need to learn that; I think we already know that," Head Coach Claude Juilen said postgame from Toronto. "I think the biggest thing right now is that we dug ourselves a hole at the beginning of the game with poor choices and bad penalties and gave them some momentum."
Boston had to kill back-to-back penalties in the opening five minutes. The penalty kill went 4-for-4 on the night, but having Brad Marchand in the box for those first two penalties wasn't ideal.
The timing also made it that the Bruins' top PK tandem - Marchand and David Backes - were in the box together during those first kills. Backes had gone to the penalty box for dropping the gloves with Nazem Kadri roff the faceoff following Toronto's first goal.
"It's tough giving up the first goal to a team that it's their home opener and it's a young team, and there's a lot of excitement in the building with everything that was going on," said defenseman John-Michael Liles. "So, giving up the first goal early, the ball got rolling for them and we got back on our heels after that and that's tough."
"Give them credit - they were on their toes to start and able to get that first goal."
The first goal came after a scramble in front, with Brown swooping in to roof the loose puck. Toronto's second goal, at 11:56 into the first, came off the rush, with Mitch Marner scoring his first NHL goal.
"It was a weird game for me - my stick just stuck in the pad while I was moving there," said Bruins netminder Anton Khudobin, who made 20 saves in his first start of the season. "He made a pretty good shot, no doubt, but at the same time, it was an easy goal by me."
The plan heading into the morning had been for Tuukka Rask to start, but Khudobin got the call.
"Tuukka's a little bit sore and Khudobin was scheduled to play one of the three [games on this road trip]," said Julien. "So because of that situation, we felt that it was the right decision to play him tonight."
Julien's intuition told him that Rask would be ready to go for Monday in Winnipeg, but stressed that "we have to take it day by day."
Even if Rask was questionable to start in Toronto, Khudobin was prepared.
"I felt all right, but start wasn't good - my start wasn't good at all," Khudobin admitted. "And 9 shots, three goals, kind of a little frustration, I would say."
"In the second period, I found my game - wasn't a lot of shots, but I started feeling the puck more," said the netminder.
The Bruins were only trailing 3-1 at that point, but couldn't generate the offense they needed.
"We told the guys they were going to be a tight-checking team and we had to fight to get to those positions and that's where I think our team didn't do a good enough job of battling, even to get to the front of the net," said Julien. "The bottom line: we need to compete and battle harder, and we didn't do that well enough."
Pastrnak led the way with six shots on goal and the Bruins' lone tally. He nearly made it a one-goal game off a point-blank feed from Brad Marchand late in the second, but Leafs netminder Frederik Andersen made the stop.
Video: BOS@TOR: Pastrnak buries Liles' feed with one-timer
Milan Michalek redirected a drive through traffic to give Toronto a 4-1 lead early in the third.
"I think it was frustrating around the net," said Colin Miller. "They created a lot of opportunities. They were good at getting their sticks on pucks, battling through guys around the net, so I think that caused us some problems. "
The Bruins had a tough night in the faceoff circle, ending the game at 38 percent on the draw. With Patrice Bergeron still back in Boston recovering from a day-to-day lower-body injury, David Backes was tasked with taking 21 of the Bruins' 52 faceoffs.
"Well, you know, we're always going to look at the losses and start whining about who's not here," said Julien. "And we were fine in Columbus, so that's certainly not an excuse and I think our guys can be better there."
"And that's not just the centermans - I think the guys can come in and help out for loose pucks. I thought at times it was a tie, but our forwards or our D's lost the battle for loose pucks…I think that hurt us a lot."
Ultimately, the Bruins showed no ounce of confusion as to why Saturday night's game ended up in the loss column.
"We need to be a little bit more focused," said Julien. "Sometimes as a team, but more as individuals, because it just takes one weak link to really throw everything off, so we need some guys to get better focus there and hopefully they can get better at it."
Following Saturday's loss to Toronto, the Bruins were set to travel to Winnipeg, where they will end their three-game, season-opening road trip on Monday night against the Jets.
"I think we need to have everybody going in the same direction," said Captain Zdeno Chara. "Five guys on the ice being on the same page."
"I thought we had that at times, but obviously for most of the game, we didn't, and we need to improve that part of our game."
Video: Hear from the Bruins after their 4-1 loss in Toronto