Geekie’s winner came off a rocket from the blue line that seemingly only the Boston winger saw. With everyone in the building looking for the puck, Geekie pointed to it, buried in the padded base in Montreal goalie Samuel Montembeault’s net.

“[Mason Lohrei] was just telling me that he thought it was [in, too],” said Geekie. “It took me a minute to think. I just saw [Elias Lindholm] looking up in the air, so I wasn’t quite sure, either, but I saw a little black thing in the net. Figured the camera didn’t go that far over, so just hoped for the best. I’m glad I was right.”

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The referees took a second look to confirm, setting off a second storm of celebrations by the towel-waving Garden denizens.

“No,” said a smiling David Pastrnak, when asked if he saw Geekie’s winner. “I honestly thought that the goalie had it under his pad. That’s what I thought. When he got up and he didn’t have it there, then I thought it might have been probably up to the netting or something, but I didn’t see it.”

The victory was all the sweeter as Boston defenseman Nikita Zadorov appeared to dodge what looked like a potentially nasty injury after a second-period collision with Zachary Bolduc and a subsequent awkward tumble to the ice.

“Warrior,” said Pastrnak. “Obviously it was an ugly looking play and just to show how tough he is and how much he means to the group and how much he cares about the group. So, credit to him. He came back and we are all happy.”

Much to the crowd’s chagrin, there were no fisticuffs off the opening face-off this time around and very little to get excited about over the first 20 minutes. Boston was credited with just two shots on goal during a first period where the home team was just a tick off on most plays.

Cole Caufield, fresh off an Olympic snub from Uncle Sam, continued his torrid season, scoring the first of his three goals to give Montreal a 1-0 lead.

Canadiens forward Cole Caufield scored a hat trick, but the Bruins got the last laugh in a comeback win over Montreal.Matthew J. Lee/Globe Staff

Caufield split a pair of defenders through the slot, collected a feathery pass from Mike Matheson, and zipped one over the glove of Jeremy Swayman (22 saves).

Pastrnak nearly tied the game with 11 seconds left in the period when his slot shot beat Montembeault, but it hit the post to the Montreal goalie’s left. The goal horn sounded and the towels waved, but it was all for naught.

“It was not good,” Bruins coach Marco Sturm said of the first period. “It was just a flat. For some reason it was very quiet, no energy, we made some really bad mistakes. Yeah, so it was a good response after that for sure.”

Montreal maintained its one-goal lead after the second period as the teams traded power-play goals to make it 3-2.

The Bruins tied it when Viktor Arvidsson buried his own rebound at the goal mouth with Montreal’s Noah Dobson (interference) in the box.

Caufield scored his second of the night, a wicked, heat-seeking power-play snipe from just above the goal line to Swayman’s right.

The Bruins went back on the power play (Kaiden Guhle for high sticking) and evened it when Geekie scored his 27th.

It came off a great effort from Pastrnak, who collected a stretch pass from Charlie McAvoy, curled through the slot, popped an airborne pass to himself, and drew a pair of defenders — and Montembeault — with him before firing it to Geekie, who settled it and popped it in the open net for his 99th career goal and a 2-2 tie.

Pastrnak was called for interference — Montreal’s Mike Evans clearly flopped — and again it was Caufield wreaking havoc.

From nearly the same spot above the goal line, the 5-foot-8-inch dynamo whistled one past Swayman for his 29th. It caused a brief blizzard of hats from our neighbors to the north, celebrating Caufield’s second career hat trick and the first by a Canadien on Boston ice since Mark Recchi back in 1996.

Rookie Fraser Minten tied it again with a nifty backhander at 13:55. Tanner Jeannot drew a holding call off the ensuing face-off, setting the stage for Geekie’s power-play winner just 12 seconds after Minten’s strike.

“We didn’t come out very strong today,” said Geekie. “But to be able to come back in the third and put together a solid performance — at the end of the day — to get the 2 points is all that matters.”

Jim McBride can be reached at james.mcbride@globe.com. Follow him @globejimmcbride.