Matthews cut it to 2-1 at 12:06, scoring on a rebound off William Nylander's shot that hit the post with Ullmark out of position. It was his first goal in five games.
"I thought we were just hunting pucks really well, turning them over, attacking," Matthews said. "I thought we had more of an attack mentality tonight instead of trying to make the extra play and I think it paid off. We had a lot of really good shifts."
Max Domi tied it 2-2 at 2:11 of the third period when he took a pass from Nicholas Robertson and deked Ullmark with a backhand. It was his first goal with Toronto.
"It feels good to contribute, but that [stuff] is irrelevant when you don't win," Domi said. "Obviously you want to come away with two points there, but the boys battled back and showed a lot of character against a real good team, a well-coached team. They're a heck of a hockey club for a reason. A good test, but I think our group showed what we are capable of, and if we find a way to string 60 minutes together like that, we'll be a tough team to beat as well."
NOTES: Pastrnak had a game-high 10 shots on goal. He scored the 66th game-opening goal of his NHL career, passing Phil Esposito (65) for the fourth-most in Bruins history. He trails Patrice Bergeron (89), Johnny Bucyk (85), and Marchand (75). … It was the 18th overtime goal for Marchand, the fourth most in NHL history, behind Alex Ovechkin (25), Sidney Crosby (20) and Jaromir Jagr (19). … Maple Leafs forward Noah Gregor had one shot on goal in 9:58 of ice time in his 200th NHL game. ... The Bruins won their fifth straight game against the Maple Leafs.