BOSTON — With less than a minute left in overtime Tuesday night, Bruins star David Pastrnak was gassed and looking for a line change. Instead, he scored the winning goal for Boston in Calgary.

After the Bruins and Flames tied the score at 3-3 in the extra frame, B defenseman Charlie McAvoy fended off Calgary’s Nazim Kadri, who had made it into the Boston goal. In the end, Pastrnak had the puck and quickly shot it to McAvoy, hoping to get a chance to get off the ice after a long overtime shift.

But McAvoy wanted a change of his own. He turned while running up the neutral zone and sent the puck back to Pastrnak, who then skated into the Calgary zone and fired a shot into the net from the right circle. Pastrnak just wanted to get the shot on goal and maybe get a whistle so Boston could make a substitution.

Instead, his wrister beat Calgary’s Dustin Wolf to give Boston a 4-3 overtime win. For the Bruins, who were down 3-1 at the start of the third period, it was the culmination of a solid comeback on the road.

Pastrnak sounded somewhat surprised that the shot resulted in his third game-winning goal of the season and his first since Nov. 12 in St. Louis. But he certainly wasn’t complaining after the win.

Pastrnak’s funny exchange with McAvoy before winning the game

Since there is a lot of space on the ice, overtime is tiring. Pastrnak was on the ice for more than 2:30 minutes in overtime Tuesday night, and his final shift was his longest, needing 48 seconds before scoring the game-winner.

So you can understand why he was a little upset before ripping the puck off Wolf. The same goes for McAvoy, who was on the ice for 42 seconds in that last shift.

“We were both out there for a long time and I yelled at him to keep it so I could change. He just dropped it to me and said, ‘You keep it,’ and he went to change, so it was kind of funny,” Pastrnak told reporters after the win. “Long shift. That’s how it is with overtime. It goes up and down sometimes.”

“There was still a minute left, so I just wanted to put it in the net, maybe get a whistle, and luckily the shot went in,” Pastrnak added.

Pastrnak played a team-best 23:06 in his 30 shifts on Tuesday night. His overtime winner was his 12th goal of the season and his fourth in the last eight games. Brad Marchand leads all Bruins skaters with 13 goals, but Pastrnak leads the team with 33 points.

Bruins come back with two goals in the third period

Without the Bruins’ comeback in the third period, Pastrnak’s game-winner would never have been possible. Boston trailed 3-1 heading into the final period of regulation time, but scored two goals in a span of 2:37 to tie the game.

Morgan Geekie grabbed a rebound just 4:14 into the game, and Marc McLaughlin made it 3-3 when he grabbed his own rebound at 6:51. The Bruins were the aggressors in the third period, defeating Calgary 15-5.

“Really proud of the performance in the third period,” said interim coach Joe Sacco. “Our boys showed a lot of determination and a never-say-die attitude and were in a good mood. We did it right and created a lot of good chances. When you play like that, the outcome will usually affect the process and it takes care of itself out there.

“You play until the final whistle and everything is ready to play,” Pastrnak said. “We’ve already been through some tough times this season, so it’s important for us to show that we’ve learned and won’t give up. We will fight.”

The Bruins continued their fight in overtime, putting four shots on net while keeping the Flames from scoring on Jeremy Swayman, who made 20 saves on the night. Boston beat Calgary in that game 35-23.

Tuesday night marked just the third time Boston won a game after trailing after two periods and improving to 3-12 this season. It was the first time the Flames lost a game while taking a two-game lead, as Calgary was 7-0-0 entering the game in that scenario.

The Bruins have now won six of their last eight games and are 2-2 in their current five-game road game. They will complete this trip with a visit to the Edmonton Oilers on Thursday evening.