Komarov's tip-in at 9:02 trimmed the Bruins' lead to one goal. Defenseman Morgan Rielly kept the puck in at the left point, and his wrist shot went off Komarov's stick at the left hash mark before eluding Rask.
The Maple Leafs kept pressuring Boston and tied the score at 11:31 when defenseman Matt Hunwick kept the puck in at the left point, turned and fired. Kadri, stationed between the circles, deflected the puck past Rask.
Komarov and Kadri each had a goal and an assist, and defenseman Roman Polak had two assists. Goaltender James Reimer made 39 saves in his 200th NHL game.
"I feel like we executed well," Kadri said. "Obviously the start of that third period wasn't too ideal, but that was a character win, being able to come back to fight right through it. And obviously that power-play goal; it's a power play that's been struggling, so that's definitely going to get our confidence up."
The Bruins (26-18-6) lost their second in a row despite two goals from Brad Marchand, who has seven goals in his past seven games. Krejci had a goal and an assist, David Pastrnak had two assists and Rask finished with 31 saves but Boston lost for the fifth time this season after taking a two-goal lead at home.
"I thought we learned from the beginning of the season," Krejci said. "We got a lot better. But today I thought I thought we came out hard. We came out, in the third period especially, to win the game. We got two quick goals. I feel like after that we kind of stopped playing on our toes and we started playing on our heels. You can maybe talk about a couple of lucky bounces on their side, a couple of tips in the high slot. Just kind of tough luck, but like I said I guess we stopped playing to win after we scored those two quick goals."
Marchand cashed the rebound of a Jimmy Hayes shot at 9:37 of the first period to give the Bruins a 1-0 lead. Toronto coach Mike Babcock challenged the goal, claiming goaltender interference on Beleskey, but it stood after a review.