James van Riemsdyk (second playoff goal) and Auston Matthews (first) also scored goals for Toronto, which now trails the best-of-seven series 2-1. The Bruins won the first two games convincingly: 5-1 and 7-3.
Game 4 is Thursday night in Toronto.
Adam McQuaid and Zdeno Chara each had his first goal of the series for Boston.
Toronto goalie Frederik Andersen, who was pulled in the first period of Game 2 after giving up three goals on five shots, finished with 40 saves.
Boston netminder Tuukka Rask made 26 saves.
Marleau's second tally came with 3:35 remaining in the game. Marleau finished off a two-on-one chance with Tomas Plekanec by lifting a puck past Rask glove-side. Matthews gave the Maple Leafs the lead for good late in the second period.
The Maple Leafs went 1-for-1 on the power play while holding the Bruins scoreless on one attempt. Toronto is 2-for-8 on the series with the extra man while Boston is 5-for-11.
Boston's top line of Brad Marchand, David Pastrnak and Patrice Bergeron was held scoreless after totaling 20 points over the first two games of the series.
Toronto played without Leo Komarov, who missed Game 3 with a lower-body injury.
Riley Nash returned to the Bruins' lineup after missing the first two games of the series recovering from an ear laceration. Tommy Wingels (undisclosed) skated Monday morning, but did not play. Matt Grzelcyk (lower body) also sat out for Boston.
After trailing for six straight periods, the Maple Leafs took their first lead when van Riemsdyk forced a rebound past Rask for a power-play goal with 2:55 left in the first period. The score came seven seconds after Nash took a delay-of-game penalty.
McQuaid pulled the Bruins even with a slap shot that beat Andersen from the point 3:06 into the second. The tie was short-lived, as Marleau directed a well-placed pass from Mitch Marner past Rask to restore Toronto's one-goal lead with 16:11 remaining in the second.
Chara struck on a close-range, side-angle wrister that deflected in off of Andersen to tie the game again with 13:41 left in the second. Matthews put the Leafs ahead 3-2 with 5:13 to play before the third on his top-shelf wrister from the left circle.
Play was stopped with under nine minutes left in the third when McQuaid was hit in the neck area by a puck off van Riemsdyk's stick. The Bruins defenseman was tended to on the ice before getting up and heading back to the locker room.
--Field Level Media
Boston | Toronto | |
Sean Kuraly 2 | Points | Patrick Marleau 2 |
Zdeno Chara 1 | Goals | Patrick Marleau 2 |
Sean Kuraly 2 | Assists | Mitchell Marner 2 |
N/A | Power Play Goals | James van Riemsdyk 1 |
N/A | Short Handed Goals | N/A |
Tuukka Rask .867 | Save Percentage | Frederik Andersen .952 |
Tuukka Rask 26 | Saves | Frederik Andersen 40 |
Team | Shots | Goals | Power Play | Penalty Kill | Penalty Mins | Face Offs Won |
Boston | 42 | 2 | 0-1 | 0-1 | 4 | 34 |
Toronto | 30 | 4 | 1-1 | 1-1 | 4 | 36 |