A better version of themselves, as if they had jumped into a souped-up, not-so-distant throwback machine to the previous two seasons, the Bruins rallied from 1-0 and 2-1 deficits on Saturday night to score a 4-3 overtime loss on the Maple Leafs at TD Garden.

Brad Marchand, goalless in the first eight games of the season, netted the winner 2:26 into the three-on-three extra session, banking in a backhander after swarming the net with David Pastrnak. The win, buoyed by Jeremy Swayman’s 20 saves, ended a three-game losing streak and moved the Black and Gold back to .500 (4-4-1) for the first time in two weeks.

“Just details – I thought our details were really good tonight,” said Marchand, noting the change in attitude and approach. “Obviously you’re not going to be completely perfect, which we weren’t – but we were definitely better. And that’s where you win and lose games, in the details, especially against a team like (the Leafs) with that offense that scores, and has some big weapons. Details are so much more important. So it was a good evening.”

Pastrnak (power play), Justin Brazeau and Mark Kastelic also scored for the Bruins, who hope to turn the win into a momentum builder when they take on the Flyers on Causeway Street on Tuesday night.

Having led in each of the previous three games (by a total of 106-82), the Bruins ended the night with a 34-23 lead, their largest margin of the season. Center Charlie Coyle and defenseman Brandon Carlo were the only Bruins not to land a shot on goaltender Anthony Stolarz.

The Bruins were 1:17 away from a 3-2 victory when Auston Matthews (goal No. 4) scored the tying goal. While crossing the low slot, the Leafs’ best shooter tapped Mitch Marner’s shot/pass from 15 yards to the ball, which was fired just inside the blue line. The Leafs net was empty, as was the Bruins’ low coverage.

“Sometimes you need a game like this, a rivalry,” said Pastrnak, who increased his goal total for the club to six (a pace of 55). “Toronto, nothing better, is playing against a very good, highly qualified team on Saturday night. You have to do your best, otherwise they will embarrass you out there. No excuses today. Everyone had to be at their best, and for the most part we were. We didn’t finish the game in 60, but there are a few experienced players who make a sick move at the end and score a goal. But in the end the score was deserved, for both parties, I think.”

After scoring just three goals in their previous three games, the Bruins connected three times in the second period and took the 3-2 lead into the final period of regulation.

The three previous defeats and lack of goals had not been the main concern, Pastrnak said.

“I don’t think we were worried about scoring, but more about the way we want to play,” he added. “I think that was more our focus. We know why we didn’t score, because we didn’t spend enough time in the offensive zone. We want to get better at it, but it doesn’t happen overnight. We have to take it one day at a time, one step at a time, and today is a great day.”

The Leafs were the first to dent the net, breaking the scoreless tie 35 seconds after the first intermission. Matthews dragged the puck to the front of the net on a rush from the left sideline and Matthew Knies picked up a loose puck on his linemate’s attempt to take a 1-0 lead.

Just over two minutes later, the Bruins had tied the knot, with Pastrnak wiring his patented one-timer for a power-play attack from the spot in the left circle. Marchand made the feed and moved diagonally across the slot after an attack from the right post.

The Leafs took the lead again, 2-1, with the teams skating with four players apiece. Morgan Rielly moved a step or two behind Marchand and cashed in a one-timer off an accurate Matthews feed. Details: Lose your man, pay the price.

But the Bruins took the lead for the first time that night when they made a pair of shots just 36 seconds apart.

The big Brazeau, who also had a spot on the second power play unit, punched in the 2-2 equalizer at 12:38. It was the last of three close-range attempts, heading home his shot from close range to the right post after efforts from Matt Poitras and Trent Frederic.

Kastelic was all alone, parked near the right post, when Johnny Beecher sent a backhand relay from the left corner at 1:14 p.m. Acquired in the trade that sent Linus Ullmark to Ottawa in June, Kastelic scored his third goal in the Black and Gold. The 6-foot-1 center never scored more than seven in a season.

The Bruins didn’t score in the opening period, but their overall effort produced their best stretch of the season. If their shooting vision had been sharper – especially Frederic, Poitras and Pavel Zacha – they could have left the period with a two or three goal lead.

From start to finish, it was much more the team and the result that coach Jim Montgomery had the past two seasons when he racked up 112 regular-season wins.

“Right,” he said. “The speed at which we played in all three zones. Especially our control speed. But also how smart we were with the puck.”

Kevin Paul Dupont can be reached at [email protected].