The Toronto Maple Leafs fired four shots on Jeremy Swayman inside the first 90 seconds Saturday.

The club was fishing the puck out of its net moments later after the Bruins capitalized on a mistake.

Toronto got a 4-on-3 power play early in the second period that failed to connect before superstar Auston Matthews beat the Boston goaltender to a loose puck only to have his golden opportunity agonizingly find iron. The home side was up 2-0 a minute later.

Mental errors, special teams, missed chances and a superior performance in the opposite crease have been hallmarks of recent Leafs post-seasons.

That script played out again inside an electric TD Garden.

Swayman was outstanding in making 35 saves and Jake DeBrusk scored twice as part of a three-point night in Boston's 5-1 victory over Toronto to open the teams' first-round playoff series.

"They're a very patient team," said Matthews, who led the NHL with an outrageous 69 goals in the regular season. "Executed on the mistakes that we made.

"Got a taste of what this series is all about – we've got to elevate our game."

John Beecher, Brandon Carlo and Trent Frederic, into an empty net, also scored for Boston. Brad Marchand and Charlie McAvoy had two assists each as the Bruins continued their dominance over the Leafs following a perfect 4-0-0 regular season.

David Kampf replied for Toronto, which handed the Bruins five power plays on mostly undisciplined or careless sequences — Boston connected on two — and went 0-for-3 on its man advantages. Ilya Samsonov stopped 19 shots.

Game 2 of the best-of-seven series goes Monday.

The Leafs winger William Nylander sat out with an undisclosed injury — the first game he's missed for anything other than illness since November 2016.

"We've played without guys at different times and we've handled it very well," Toronto head coach Sheldon Keefe said. "We didn't handle it very well tonight. We certainly missed him.

"But he has nothing to do with us taking too many penalties or giving up a 2-on-1."

Toronto won its first post-season series in 19 years last spring before losing to the Florida Panthers in the second round. Boston had a record-breaking 2022-23 campaign, but also fell to the Panthers.

"We can take a lot from this game and try to course correct," said Matthews, whose team lost its playoff opener at home to the Tampa Bay Lightning some 12 months ago before winning four of the next five to advance for the first time since 2004. "We've just got to come out and elevate our game."

Toronto and Boston are meeting in the first round for the fourth time in the last 12 years. The Bruins took the three previous series — in 2013, 2018 and 2019 — in seven games.

After the visitors directed that early salvo at Swayman, Boston took a 1-0 lead at 2:26 when Beecher scored his first-career playoff goal on an odd-man rush.

Samsonov heard a symphony of iron behind him as the opening period progressed. Coyle hit the post before both McAvoy and Pavel Zacha chimed shots off the crossbar.

Bruising Bruins forward Pat Maroon also nearly put Leafs defenceman Timothy Liljegren into Boston's bench inside a pulsating rink that watched Toronto winger Max Domi cross-check and slash Marchand before the opening faceoff.

The Leafs couldn't connect on their 4-on-3 man advantage to start the second and Calle Jarnkrok — back in the lineup following a long injury absence — was stopped on a partial break moments later.

"Really slow, disconnected," Keefe said of his power play. "Not good enough."

Matthews won the race with Swayman shortly after that, but clanked the effort off the near post.

"Huge," Bruins head coach Jim Montgomery said. "Thought it was 1-1 as soon as he got by Sway. We've got to be better in those areas."

The Bruins made the Leafs pay for that miss.

Carlo blasted a shot past Samsonov with Leafs forward Pontus Holmberg screening his netminder at 5:47 for a 2-0 lead.

Boston's under-fire power play — until Saturday, that is — then went to work.

DeBrusk snapped his first through another screen with Matthews off for high-sticking at 15:02.

Domi then took a slashing penalty and DeBrusk added his second for a 4-0 advantage at 17:34.

"I understand what he's trying to do," Keefe said of Domi. "Crossed the line there."

"We've got to be a little bit more prepared to tone it down," added Leafs winger Tyler Bertuzzi, who took a penalty in the first. "Not be so emotionally invested."

The Leafs got a fourth-line goal at 1:39 when Kampf beat Swayman.

But it wasn't nearly enough for a team that will await Nylander's status for Monday.

"Tough to go into a playoff without him," Keefe said. "But not the storyline here for us.

"There's other things we need to do a lot better."

Hurricanes 3, Islanders 1

Stefan Noesen grabbed a loose puck atop the crease and pushed it past Semyon Varlamov early in the third period to help the Carolina Hurricanes beat the New York Islanders 3-1 to open their NHL playoff series.

Game 2 of the best-of-7 first-round series is Monday night.

Noesen's collect-and-finish score at 3:44 of the period finally pushed Carolina into the lead, then Martin Necas added an empty-net clincher from beyond the blue line with 1:32 to go. Those capped a grinding outing for the Hurricanes, who needed plenty of big stops from Frederik Andersen to hang on at home.