Trent Frederic and Jake DeBrusk scored for the Bruins, who are the No. 2 seed from the Atlantic Division. Jeremy Swayman, who made 35 saves in a 5-1 win in Game 1 before backing up Linus Ullmark in Game 2, made 28 saves.
“Any time I get a chance to play, I’m going to do whatever I can to help this team win,” Swayman said. “Whether it’s back-to-back to every other game, I’m just really grateful every time I do get a chance, and that’s all I worry about.”
“I’m never going to expect anything. I’m going to earn it. That’s all I care about.”
Matthew Knies and Tyler Bertuzzi scored, and Samsonov made 30 saves for the Maple Leafs, who are the No. 3 seed from the Atlantic. Toronto played its third straight game without forward William Nylander because of an undisclosed injury.
Boston leads the best-of-7 series 2-1. Game 4 will be in Toronto on Saturday.
“Little mistakes at very important times that end up in our net, but in general I just didn’t think we got to our game nearly as much tonight as we did in the others,” Toronto coach Sheldon Keefe said. “Credit to Boston, they played hard, made it hard to get through the neutral zone, and I didn’t think we did enough to manage through that.”
Knies gave the Maple Leafs a 1-0 lead at 13:10 of the second period. Mitch Marner took a drop pass from Joel Edmundson as he skated through the right circle and found Knies with a seam pass for a tap in at the left post.
Frederic tied it 1-1 at 17:37 when he beat Samsonov short side with a wrist shot from the left circle.
DeBrusk scored his third power-play goal of the playoffs to put the Bruins up 2-1 at 1:07 of the third period. He put in a rebound at the top of the crease off Marchand’s shot.