Boston fell to 4-5-1 as it failed to consistently generate quality chances against a Philadelphia club that allowed nearly 4.5 goals per game, second-worst in the NHL.

The good news is that the Bruins stayed out of the penalty box through the first 20 minutes. The flip side is that they also stayed off the scoresheet.

Joonas Korpisalo shined early and late as the Boston goaltender made his first start in nearly two weeks.

Korpisalo made back-to-back stops on Philadelphia winger Bobby Brink, first deflecting one with the blocker and then muffling the follow-up with his right pad.

It was part of a mini-Flyers surge made possible by a ferocious forecheck that kept defensemen Charlie McAvoy and Mason Lohrei on the ice for an extended period.

Just when it looked like Philly goaltender Samuel Ersson wasn’t breaking a sweat, Cole Koepke woke him up with an off-the-mask shot from the blue line.

Boston put together some nice offense on a five-on-three power play as Scott Laughton cross-checked Brad Marchand and 23 seconds later Travis Sanheim dragged David Pastrnak into the slot.

The Bruins were efficient, with Marchand getting the best chance, but Ersson denied him.

The power play save came from Korpisalo, who took a wrist shot from Garnet Hathaway on a two-on-one from Laughton, who had just come out of the box.

Ersson denied Pavel Zacha (nice pass from Matt Poitras) and Elias Lindholm (point blank from a flat from Andrew Peeke), and Peeke sent in a screamer from the far post to close the period.

Korpisalo made several Grade-A stops, including denying Ryan Poehling on a partial break-in.

Rasmus Ristolainen, last seen hurting Poitras with a big hit at the buzzer in a preseason game, tried to get the Flyers going again with a riser from the blue line, but Korpisalo gobbled it up.

Pastrnak temporarily neutralized Jamie Drysdale with a missile just inside the blue line that hit the Flyers defenseman in the gut. The Bruins peppered Ersson for a good 30 seconds as Drysdale tried to get up.

He eventually made it to the bench and went down the tunnel before returning a few shifts later.

Philadelphia broke the ice when an unmarked Tyson Foerster hit a low wrist shot inside Korpisalo’s five hole.

The Flyers got on the power play a few seconds later (Koepke for a sharp shot), but couldn’t shake Korpisalo and increase their advantage.

Boston got another chance on the power play when Morgan Frost put Morgan Geekie in the chops with a high stick. Despite plenty of zone time, the Bruins failed to make a single shot with the man advantage and went into the locker room, 1-0, after 40 minutes.

Jim McBride can be contacted at [email protected]. Follow him @globejimmcbride.