TORONTO — With the Maple Leafs buzzing and Scotiabank Arena rocking after Toronto equalized early in Wednesday's second period, the Bruins needed a push from their dormant stars.
David Pastrnak, Brad Marchand and Patrice Bergeron delivered, and now the Eastern Conference quarterfinal is heading back to Boston tied at two games apiece.
Pastrnak scored twice in quick succession, Marchand had a goal and two assists, and the Bruins survived a late surge to beat the Leafs 6-4.
Toronto had a chance to go up 3-1 in a series for the first time in 32 years, but instead will be kicking itself following a game where it fell behind 2-0 and 5-2 before a late rally fell short.
"We had real good energy," Leafs head coach Mike Babcock said. "I didn't think we had the kind of brain all the time that we wanted. Turned the puck over, two real big mistakes on the penalty kill.
"Just got in our own way a little bit."
The line of Pasternak, Marchand and Bergeron was held in check with six points — including just two at 5 on 5 — through nine periods to start the series, but had matched that total by the time Boston made it 4-2 five minutes into the second.
Bruins head coach Bruce Cassidy moved Pastrnak away from the triumvirate much of the night only to reunite the three after the Leafs tied it.
The sniper finished off a 2-on-1 with Marchand on a play started by Bergeron to put Boston back in front at 3:16 of the second. Pastrnak then took a slick backhand feed from Marchand on a power play to snap home his second just 95 seconds later.
"It's not easy to win in this building," said Pastrnak, who mostly played on a line with David Krejci. "A hell of a win."
Charlie McAvoy, with a goal and an assist, Zdeno Chara and Joakim Nordstrom, into an empty net, also scored for Boston, which got 38 stops from Tuukka Rask.
Auston Matthews, with two, Zach Hyman and Travis Dermott replied for Toronto. Frederik Andersen made 25 saves, while Morgan Rielly added two assists.
The Bruins restored home-ice advantage in the series, with Game 5 set for Friday at TD Garden. Game 6 goes Sunday back at Scotiabank Arena.
Toronto held a significant edge in 5-on-5 play with nearly 62 per cent puck possession (70 shot attempts to 43), but was undone by mental errors and an inability to connect on the power play early.
"We did a lot of good things," said Leafs centre John Tavares, who along with Hyman and Mitch Marner have been tasked with going toe-to-toe against the Bergeron line. "We generated a lot of chances, got a lot of pucks to the net.
"We didn't have our best start tonight, but we gave ourselves a good chance."
Coming into these playoffs, Pastrnak had registered 27 points his last 15 games against Toronto, but put up just one assist in the series prior to Wednesday. The line of Pastrnak, Marchand and Bergeron alone combined for 30 points in last spring's seven-game victory over the Leafs in the first round.
Rask, who didn't look good on Toronto's tying goal in the second, made up for that gaffe with a great toe save on Connor Brown at the lip of the crease later in the period in the wake of Pastrnak's double.
Matthews hit the post early in the third, but the Bruins went up 5-2 at 5:39 when Chara fired a shot through a terrific Bergeron screen. At 42 years, 30 days, Boston's captain became the second-oldest defenceman in NHL history to score a goal in the playoffs.
Matthews got the Leafs within two on the power play with 8:08 left in regulation as Toronto started to press before Dermott made it 5-4 through traffic with 6:33 remaining inside a boisterous Scotiabank Arena.
Marchand hit the post with just over two minutes to go, but Boston held on late before Nordstrom scored into an empty net.
Down 2-1 after 20 minutes, the Leafs got level 1:07 into the middle period when Matthews fired a shot that squeezed between Rask's left arm and body for his second in as many games after being held off the scoresheet in Boston.
Boston jumped out to a 1-0 lead on the power play at 3:03 of the first when McAvoy wired a shot blocker side on Andersen to silence the crowd of 19,638 that had been in full voice moments earlier.
The Bruins made it 2-0 when Danton Heinen — Pastrnak's replacement on the top line — fed a pass in front to Marchand, who scored his second of the series at 6:38.
Andersen made a great save on Coyle in the slot to keep his team down by two before Toronto started to find its legs.
The Leafs couldn't do much of anything on consecutive power plays, but Hyman got his team on the board just after the second penalty expired, tipping Rielly's point shot with 2:05 left in the period.
"They came pretty hard and were able to take advantage of some of their chances," Andersen said. "They probably came out a bit harder than we did."
That will have to change for Toronto in Game 5 or the Leafs could be facing elimination at home Sunday.
Notes: Chris Chelios is the oldest defenceman in NHL history to score a playoff goal at 45 years, 86 days. ... Game 7, if necessary, would be Tuesday at TD Garden. ... Canadian hip hop artist Drake, Toronto Raptors head coach Nick Nurse and Rob Baker of The Tragically Hip were in attendance.
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Joshua Clipperton, The Canadian Press