Connor Bunnaman and Mark Friedman to make their season debuts Thursday for the Flyers in Boston

Because of a rash of early-season injuries, the Flyers need to have a “next-man-up mentality,” coach Alain Vigneault said.

For Thursday’s game in Boston, that applies to defenseman Mark Friedman and center Connor Bunnaman, who will make their season debuts. They will be in the lineup because of injuries to defenseman Phil Myers and center Morgan Frost.

Friedman, a right-hander, will be on third pairing with Robert Hagg, and Bunnaman will center the fourth line and have Michael Raffl and Nic Aube-Kubel as his wingers.

Bunnaman, 22, a fourth-round selection (109th overall) in 2016, has greatly improved his speed over the last two years. Like Friedman, the 6-foot-1, 207-pound Bunnaman spent time with the AHL’s Phantoms and the Flyers last season. He had nine points, including six goals, in 29 games and was minus-21 with Lehigh Valley. In 21 games with the Flyers, he had a goal and an assist, and was plus-7.

“I thought Bunny was the most improved player in camp this year,” center Kevin Hayes said after Thursday’s morning skate. “He was flying out there and looked unbelievable. He deserves this opportunity, and I think he’s going to be a great player for us.”

The 5-11, 185-pound Friedman was selected by the Flyers in the third round (86th overall) of the 2014 draft. He had 18 points (three goals, 15 assists) and a plus-2 rating in 45 games with the Phantoms last season. He also had a six-game stint with the Flyers, collecting an assist and an “even” rating.

Vigneault said he “liked the bite” Friedman brought in his brief stay with the team last season, adding, “He was extremely hard as far as competing and battling. This year, I would say his camp was just OK, and we made that very clear to him, and he’s picked it up since then, even though he hasn’t had a chance to play. He’s been waiting for this opportunity, so I expect him to play real hard and to compete.”

His “camp wasn’t great. I’ve been practicing and sticking with it,” Friedman said. “It’s been a long time since I’ve played a game, so I just have to keep it simple.”

Playing in six NHL games and signing a two-year contract last July ($725,000 annual cap hit), Friedman said, makes him feel “a little more confident, for sure.”

The Flyers have had three players — Sean Couturier, Myers and Frost — suffer injuries over the first four games. Hayes doesn’t believe the injuries had anything to do with a shortened training camp or the fact the players didn’t have any exhibitions to get game-ready.

“I think it’s just been bad luck,” said Hayes, who grew up just outside Boston. “Tough hits. Could happen to anyone.”