Flyers goalie Carter Hart and defenseman Phil Myers made their NHL postseason debuts Sunday and looked about as nervous as 10-year veterans.

Hart was superb as he stopped 34 shots -- the only one that went past him deflected off a teammate -- and Myers scored a key goal as the fourth-seeded (for now) Flyers upset top-seeded Boston, 4-1, in a round-robin tournament opener in Toronto.

Nate Thompson, who centered Michael Raffl and Tyler Pitlick (four hits) on a fourth line that produced two goals, is amazed at the composure Hart shows for such a young goalie.

“He doesn’t look 21 to me,” Thompson said. “He’s pretty poised to me, even off the ice. He carries himself well beyond his years. He’s a true pro. He reminds me a little bit of a goalie I used to play with in Montreal, and you guys know who I mean.”

He was referring to Canadiens star Carey Price.

Hart, who turns 22 on Aug. 13, became the youngest goalie in Flyers history to win a postseason game. Pete Peeters was nearly 23 when he won a 1980 playoff game against Edmonton.

“He’s our backbone back there,” Thompson said, “and he was really good for us tonight.”

Myers, 23, who was plus-3 and led the Flyers with five shots and nine shot attempts, said he felt “a little nervous” until his first shift, “and then it just became like any other game. I kind of got in a zone out there. Just making plays. I felt good out there and I think it was a good team win. Hartsy shut the door for us and we took care of everything else.”

“I agree with Phil,” Hart said. “Once you get out there playing, the game really slows down. Obviously, it’s a little different in playoffs and we don’t have fans, so maybe that makes it a little bit different. But when the puck drops, it’s all the same, you just have to prepare and execute and play your game.”

Bruins’ trio blanked

Blanking Boston’s sensational top line -- Patrice Bergeron centering Brad Marchand and David Pastrnak -- was a key to the win. Sean Couturier, Claude Giroux, and Jake Voracek spent lots of time defending against the line, which combined for 107 goals in the pandemic-shortened regular season.

“Our guys did a good job, especially Coots’ line,” left winger Scott Laughton said. “They’re a dangerous trio and they‘re so good on the power play and five-on-five in the zone, so you have to be aware of them. I think we did a really good job in the second and third periods of staying over top of guys and not giving them too much space so our D could pinch down the wall.”

The Boston trio was a combined minus-7.

Defenseman Ivan Provorov (three blocked shots) led the Flyers with 24:51 of ice time and, along with Matt Niskanen, also played a big role in helping shut down the Bruins’ stars. Ditto Myers and Travis Sanheim.

Beating Halak (again)

Boston goalie Jaroslav Halak, 35, who played because Tuukka Rask was ill, has been around so long that, while with Montreal, he faced the Flyers in the 2008 and 2010 playoffs, going just 1-5 with a 3.58 goals-against average and an .883 save percentage against them.

His struggles against the Flyers continued Sunday.

Breakaways

Sanheim was also plus-3. ... Derek Grant won eight of 11 faceoffs (73%).