That proved to be the difference Monday night as Boston took advantage to defeat Toronto 5-2 and regain the upper hand in their NHL playoff series.
"They made less mistakes than we did and their execution level was above ours," Toronto coach Randy Carlyle said in assessing the night.
"Mistakes just killed us tonight," echoed smooth-skating defenceman Jake Gardiner, who scored his first-ever playoff goal.
The loss came before 19,746 amped-up fans inside the Air Canada Centre. Outside, a blue-and-white throng watched the game on a big screen in Maple Leaf Square as playoff hockey returned to Toronto for the first time since 2004.
"The crowd was awesome," said Leafs forward James van Riemsdyk. "One of the loudest I think I've played in front of in the NHL."
Game 4 goes Wednesday in Toronto, with the Leafs trailing 2-1 in the series.
Adam McQuaid, Rich Peverley, Nathan Horton, Daniel Paille and David Krejci — with an empty-net goal with 1:17 remaining — scored for Boston, a playoff-savvy squad which came out with an edge.
Two goals in some two minutes in the second period buried the Leafs just 50 seconds after Gardiner's goal had cut the Boston lead to 2-1. Horton and Paille, shorthanded, suddenly made it 4-1 and Toronto was facing a mountain of a comeback.
The line of Milan Lucic, Krejci and Horton finished the night with two goals and six assists. They have combined for 17 points through the first three post-season games, with five goals and 12 assists.
Future Hall of Famer Jaromir Jagr also showed off his skills, setting up a goal and controlling the puck as if it was glued to his stick.
"Vintage Jagr in the offensive zone," said Boston coach Claude Julien.
Phil Kessel accounted for the other Toronto goal in a physical game that saw Boston outhit the Leafs 51-48.
The Leafs charged hard in the third, outshooting Boston 18-6 for a 47-38 overall edge. But Tuuka Rask stood tall in the Boston goal.
"They came out in the third a desperate team," said Julien.
It was the first Leafs' home playoff game since May 4, 2004, when Toronto lost 3-2 in overtime to the Philadelphia Flyers to lose the conference semifinal 4-2. Fans were rewarded for patience with free scarves.
The last home playoff win came in that same series, a 3-1 victory on April 30, 2004.
For the Bruins, the playoffs are business as usual. Boston, which won the Cup two years ago, is in the post-season for the sixth straight year.
After being beaten 4-2 in Boston on Saturday night, the Bruins upped their game.
"I think, as a team, we played a good road game," Krejci said. "Maybe we didn't have as many chances in Game 1 (a 4-1 Boston win) but I think it was a perfect road game and I'm pretty happy about that.
"In Game 4 we know it's going to be tougher just like we knew Game 2 was going to be tougher."
The Leafs, meanwhile, were punished for their mistakes.
But they went down shooting. It was the most shots this season since they mustered 43 in a January loss to the New York Islanders.
It was the most shots allowed by the Bruins in a playoff game since Montreal's 51 in a double-overtime game on April 23, 2011. And it was the most shots allowed by the Bruins in a non-overtime playoff game since April 11, 1975, when Chicago had 56 in a 6-4 Blackhawks win.
"We hung him out to dry a couple too many times," van Riemsdyk said of Leafs goalie James Reimer, who deserved better. "That was the difference in the game."
Inside the chants of "Go Leafs Go" started early, before the warmup. Even anthem singer 2nd Lieutenant Scott Newlands got an ovation, with the crowd belting out "O Canada" with him.
Boston did its bit to quiet the crowd, which still had its moments as the night progressed. And the fans booed Bruins captain Zdeno Chara almost every time he touched the puck.
The crowd showed Kessel some love, chanting "Thank You Kessel." Unlike in Boston, where fans used the chant to taunt the former Bruin, they meant it Monday.
Toronto went with the same lineup, sitting out defencemen Michael Kostka (broken finger) and John-Michael Liles and forwards Clarke MacArthur, Frazer McLaren and Joe Colborne.
Bruins defenceman Andrew Ference returned from his one-game suspension. That allowed Julien to go back to his Game 1 defensive pairings: Chara with Dennis Seidenberg, Ference with Johnny Boychuk, and Wade Redden with McQuaid. Boston won that game 4-1.
Rookie Dougie Hamilton, who replaced Ference on Saturday, dropped out of the lineup.
Carlyle continued to do his best to keep Kessel away from Chara. Matt Frattin spent eight seconds on the ice after the opening faceoff before he headed to the bench and Kessel popped over the boards.
Kessel saw time on lines with both Tyler Bozak and Joffrey Lupul, and Nazem Kadri and Ryan Hamilton, with Frattin acting as his body double as needed on the other trio. Kessel was also deployed at times on left wing for faceoffs in the Boston end, to earn some space from the six-foot-nine Boston captain.
Toronto outshot Boston early but it was Reimer called on to make a huge save midway through the period after he gave up a rebound and Colton Orr and Carl Gunnarsson both skated past it. Tyler Seguin swooped in but Reimer stopped his close-range backhand with his blocker.
Seguin has 17 shots in the series but has yet to beat Reimer.
The Bruins mean business — Gregory Campbell introduced Leo Komarov to the tip of his stick at one point —and began to threaten. And they scored first at 13:42 when McQuaid's shot from the point beat Reimer to the stick side. The Toronto goalie looked aghast, as if the puck had done something before passing him by.
It was Boston's seventh goal of the series and the fourth scored by defencemen.
Reimer bounced back with a nice pad save on Shawn Thornton.
Boston outshot Toronto 17-13 in the first period while the Leafs held a 21-19 edge in hits.
The Bruins continued to dictate the game early in the second but Rask was forced to make back-to-back saves off Lupul and Bozak in a rare Leafs rush some five minutes in.
Boston went ahead 2-0 at 5:57 when 41-year-old Jagr, who was lively all night, stripped Ryan O'Byrne of the puck behind the goal and fed Peverley, who stuffed it past a helpless Reimer.
Jagr's assist was his 190th career NHL playoff point, tying him with Brett Hull for sixth place on the league’s all-time playoff points list.
Dion Phaneuf hit the Boston goalpost after skating in from the point and taking a marvellous pass from Nikolai Kulemin.
The Bruins continued to win the faceoff battle with Bozak, the Leafs' top faceoff man, repeatedly thrown out of the circle. Boston won 45 faceoffs to Toronto's 30.
Gardiner got the crowd out of their seats when Bruin penalty killer Chris Kelly's failed clearance went to Gardiner who skated in from the blue-line and snapped a shot over the glove of Rask at 13:45 for his first playoff goal.
The fans were still celebrating — inside and outside the building — when Lucic cruised down the left wing and sent a laser-like pass over to Horton, open at the top of the crease. He beat Reimer for his third of the playoffs at 14:35.
The Toronto goalie helped stop the scoreboard turning when he stoned Jagr on a breakaway soon after.
But the Bruins onslaught continued as Kessel gave up the puck on the power play and Paille, with Kessel nipping at his heels, raced in alone to beat Reimer with a backhand at 16:37 for his second of the playoffs.
Boston outshot Toronto 32-28 after 40 minutes.
An opportunistic Kessel closed the gap to 4-2 just 47 seconds into the third period when Rask slid out of the position and Seidenberg was unable to clear the puck. Kessel picked it up and fired it into the net over a sliding Bruin.
That earned another round of "Thank You Kessel" chants.
The Bruins got a break as the third period wound down when Rask and the defence managed to clear a Cody Franson shot and the rebounds that followed. Rask had to stop Franson again minutes later.
Boston was 0-for-3 on the power play and is 1-for-9 with the man advantage in the first three games. Toronto went 2-for-5 on the power play and is 4-for-12 in the post-season.