Captain Claude Giroux’s power play goal in overtime, his second of the game, gave the Boston Bruins their fourth loss at home this season in as many tries as the Philadelphia Flyers defeated them by a 5-4 score in sudden death.

Bruins and Flyers met at the TD Garden in NBCSN’s much-ballyhooed “Rivalry Night”, and although the B’s overcame a sluggish start and 1-0 and 2-1 deficits to gain a 4-2 advantage, quick third period goals by Flyers big guns Giroux and Wayne Simmonds evened the score with 8:39 left in regulation to set up the 3-on-3 overtime period.

The B’s once again got solid production from its special teams in the form of both power play and shorthanded goals (the second such shortie in as many games) from Patrice Bergeron and Chris Kelly respectively.

The Flyers struck first with a goal from Paris, France-born Pierre-Edouard Bellemare, who put in his own rebound after boxing out Joonas Kemppainen and getting to the puck when Tuukka Rask was unable to close his glove on the initial shot.

Boston evened the score with Brett Connolly’s first goal as a Bruin dating back to his acquisition at last February’s trade deadline. He swooped in and converted a Bergeron rebound after Giroux failed to pick him up, firing the puck into the net past starter Michal Neuvirth.

The Flyers re-took the lead right after that when Sam Gagner capitalized on a bad line change by Boston to gain some extra time and space and beat Rask with a shot to make it 2-1 on his second goal of the season.

Boston tied it up when Bergeron batted a puck out of mid-air with the man advantage late in the opening frame. The NHL’s most lethal power play unit moved the puck with authority in the offensive zone and when Loui Eriksson worked the puck to the front of the net, David Krejci’s initial shot bounced up in the air with Bergeron right at the top of the paint to knock it in. Neuwirth slumped over after that play, which was a harbinger of things to come.

As the opening frame ended, Zac Rinaldo reminded everyone of the controversy that surrounded his summer acquisition (for a 2017 third-round pick) when he hit Sean Couturier hard at the buzzer, knocking the big center out of the game. At speed, the play looked like a head shot, but when slowed down, it appeared that Rinaldo went shoulder to chest, but Couturier had his head down, appearing to brace for backside checking pressure coming from Adam McQuaid. When Rinaldo ran him, his head snapped back and Couturier went down hard. Rinaldo was assessed a 5-minute charging match penalty (game misconduct) that will likely draw some form of supplemental discipline given Rinaldo’s history. The hit looked dirty, but the unfortunate outcome was that the Flyers player was lost for the remainder of the contest.

When the second period started, Neuvirth was out of the crease and not present on the bench with an undisclosed injury, giving way to Steve Mason.

While the Flyers were on the Rinaldo power play, the B’s rubbed some salt in the wounds on a breakout, with Eriksson throwing the puck to the Philly net with Chris Kelly driving straight in at Mason. The shot hit Kelly’s skate and deflected in the net to make it a 3-2 score.

Boston added to the lead when Jimmy Hayes broke in on the right side and threw a shot at the Flyers net from a sharp angle that somehow snuck over the goal line past Mason to make it 4-2.

Boston was cruising near the halfway mark of the final frame when Colin Miller found David Pastrnak all alone in the high slot with a yawning net to hit, but somehow, Mason got his glove hand across to deny the young B what looked like a surefire goal. The NHL reviewed it, but the call on the ice of no goal stood, leaving the score at 4-2.

That opened the door for Philly’s quick strikes to tie the game and eventually force overtime, especially after the B’s did not register a single shot on Mason in the final 12 minutes and change of regulation.

Ryan Spooner took a hooking call after Michael Del Zotto all but grabbed onto Spooner’s stick while hurling himself to the ice in spectacular fashion, but it worked to perfection. The Flyers went on the 4-on-3 man advantage with Bergeron-Zdeno Chara-MQuaid unable to clear the zone before the puck worked over Giroux for the one-timer that found the back of the net past Rask.

UP

Patrice Bergeron- On the day his first child, a son named Zack was born to him and wife Stephanie, Bergeron assisted on the Connolly goal and added one of his own. As Globe scribe Amalie Benjamin said- assist, goal and baby- thats got to be some kind of newfangled trick for the new dad, who couldn’t quite pull out the win for his boy.

Brett Connolly- For the former Lightning high-end prospect, this goal was a long time coming and he didn’t miss. He also displayed speed and quickness throughout the game, though that was all he was able to generate on the score sheet. If Connolly could put it all together, the B’s will benefit and for now- finding the back of the net is a good start for him.

Chris Kelly- He got one shorthanded goal and was instrumental on the Hayes tally with a hustling back check to diffuse a Philadelphia scoring chance then transition the play back the other way. The savvy veteran is contributing this season with his typical three-zone effectiveness while also adding some early production.

DOWN

Zac Rinaldo- C’mon, man. All that talk of turning over a new leaf…it doesn’t matter if the hit was technically shoulder-to-chest contact- it was unnecessary as Couturier did not have the puck and was looking away from Rinaldo as he came in. Fair or not- Rinaldo is not going to get the benefit of the doubt on plays like that, and so he’s getting hammered in the court of public opinion right now, especially since Couturier is out with what is believed to be a concussion. Not smart, but a lot of critics said this was coming and it only took six games. C’mon man.

Tuukka Rask- At some point, you have to quit making excuses for the guy. He’s off, and this was a game the Bruins played well enough to win, save for the fact that they didn’t get some key stops from him when they needed it.  Even if you allow for the fact that Kevan Miller’s turnover behind the net leading to the first Giroux strike was not on him, he was off the angle on the Simmonds goal and simply isn’t playing like the All-Star caliber goalie the B’s need him to be. It’s not Bobrovskian on the scale of disappointments in the early season, but the Bruins and their fans have a right to expect a whole lot more than what Rask is giving them right now.

David Pastrnak- Love the kid’s talent and enthusiasm, but the turnovers continue and when he had a glittering chance to put the game away, he wasn’t able to, opening the door for the Flyers comeback. You have to grit your teeth and live with the mistakes given how hard he works and how well intentioned he is, but he’s hurting the team and needs to simplify/try to find a balance between the high-risk decisions he’s making and the natural ability we all know he has to score points in this league.

Joonas Kemppainen- At this point, I’ve seen enough. He’s soft on the puck, not assertive enough, appears to be a step behind when it matters. Most of the time he looks like he’s in the right spots but  is just not making plays. I have to think Max Talbot would give you more effective all-around play on the bottom line than this guy will at this stage.

Kevan Miller- He’s got to be better in his own end. His aborted attempt to reverse the puck led to the goal that pulled Philly back into it, and when you’re a fringe d-man, you can’t afford those kinds of mistakes. Miller is one tough nut and a rugged customer, but he doesn’t have enough in the way of talent to get by when he makes gaffes out of what should be a routine exchange. Tighten up.

Ryan Spooner- Great on the power play, but not getting it done at even strength where the advanced stats are exposing him down near the bottom of the league in puck possession. The penalty he took in OT won’t help his case either, but in his defense, Del Zotto sold that like a Sotheby’s auctioneer.

Tough loss in a game the Bruins really had on their plate to win. It won’t get any easier when they travel to Brooklyn to face the Islanders on Friday, but play away from the TD Garden has offset their poor performance at home, so we’ll see.