Bruins captain Joe Thornton, who had two assists, said the difference was Toronto goalie Ed Belfour, who made 49 saves as well as stopping all three Boston shootout attempts by Thornton, Glen Murray, and Patrice Bergeron.
''He kind of stole the show in the third," said Thornton, whose team had five power plays in that period. ''Eddie just really stoned us in the third period. We had a couple of great chances on the power play and he denied the shots, and the second period, he kind of let a couple of floaters in and really got his confidence in the third and that was the difference."
In the shootout, Eric Lindros beat Boston goalie Andrew Raycroft on a crafty backhander after Murray's failed bid. Thornton's try hit the right post, and after former Bruins captain Jason Allison missed on a backhander for the Leafs, Belfour turned back Bergeron.
In the end, it was the power play -- so effective against the Penguins Saturday -- that left them short.
''I don't know if we didn't have it set up or we didn't have it in the right place," said Murray. ''We just didn't execute, plain and simple. Their [defense] was stepping in front of our shots and they made a bunch of blocks.
''Give them credit, too. As well as they played on the [penalty killing], we didn't have our best power play, but they outplayed us on special teams."
The Bruins got off to a weak start, giving up a pair of goals in the first period. The first came as the result of a give-and-go between Lindros and winger Tie Domi. Domi, in the left circle, threw the puck across the slot to Lindros, who fired it right back on the stick of Domi and he directed it past Raycroft at 12:20.
The second goal came on the man advantage at 13:06, set up well by Allison. With Dave Scatchard off for hooking, center Jeff O'Neill had the puck at the left point. He dished it down to Allison, below the left circle, and Alllison found defenseman Bryan McCabe cutting to the net and fed him in the slot for the 2-0 lead.