BOSTON (AP) David Pastrnak helped Boston escape a first-period onslaught with a lead, then turned the next two periods into a rout.
''We talked before the game that we need to be better than what we've shown the last couple of games,'' said Pastrnak, who was held without a point Thursday night in the Bruins' loss to Vancouver.
Pastrnak and the rest of Boston's top line bounced back nicely against the Maple Leafs.
Patrice Bergeron had a goal and two assists and Brad Marchand had two assists for the Bruins, who led 1-0 after the first despite being outshot 20-6 in the opening 20 minutes.
It was the second hat trick of the season and third career for Pastrnak, Boston's 22-year-old Czech phenom who is developing into more than just a scoring threat.
''He's obviously a great talent. He's got great smarts and he's so good at getting open,'' Bergeron said. ''When you add being tenacious on the puck and winning battles that makes a big difference.''
Pastrnak took sole possession of the NHL scoring lead with 15 goals after he entered in a four-way tie for the most.
Jaroslav Halak stopped 40 shots for the Bruins, who ended Toronto's three-game winning streak and handed the Maple Leafs their first road loss of the season.
John Tavares scored the only goal for Toronto, and Garret Sparks finished with 29 saves.
Pastrnak scored twice in the second period and added his third of the night with a one-timer from the left circle with 5:56 left to play.
Joakim Nordstrom scored again for Boston just 26 seconds later to seal it for the Bruins, who won the first meeting of the Original Six rivals after going 1-3 against the Maple Leafs last season.
''We didn't get it done when we had all those opportunities early,'' Toronto coach Mike Babcock said.
Halak got the start in the Bruins' first game since the club granted a leave of absence to Tuukka Rask for undisclosed personal reasons. Halak stopped all 20 shots he faced in the first period, keeping the Bruins in it despite a slow start.
''The shot count was in their favor by a big difference but I think in the second we evened it out pretty closely and we did a good job capitalizing on some scoring chances that we had,'' Boston captain Zdeno Chara said.
After Pastrnak set up Bergeron for the first goal of the game, Bergeron returned the favor 5:46 into the second with a pass from behind the net for a one-timer from the left circle to give Boston a 2-0 lead.
Pastrnak made it 3-0 on a power-play goal 10:24 into the second, tipping in a shot by Marchand after a cross-ice pass from Bergeron with 36 seconds left on a hooking penalty on Toronto's Martin Marincin.
Tavares scored for Toronto with 30 seconds left in the second period.
''We got off to a good start,'' Toronto's Mitch Marner said. ''The second period, we gave up too many opportunities. We let them take the game to us.
NOTES: Halak was pulled Thursday against Vancouver after allowing five goals on 19 shots. ... The Leafs allowed their most goals since a 3-1 loss to Calgary on Oct. 29. ... With Rask unavailable, the Bruins called up G Dan Vladar from AHL Providence on an emergency basis. ... Bergeron's goal in the first was the 298th of his career.
Maple Leafs: At Los Angeles on Tuesday night.
Bruins: Host Vegas on Sunday night.
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