The Bruins’ league-leading penalty kill took a hit on Thursday when the team announced that Derek Forbort was placed long-term injured reserve, meaning he’ll have to miss 10 games and 24 days.

The veteran left shot defenseman has been battling a groin injury since the start of the training camp and hasn’t been able to shake it. He sat out four games earlier in the season but he hasn’t been able to settle it down.

“It’s a lower body injury that’s been there since training camp. I think at one point we gave him five days off and it was doing well, but the nine games in 16 days, with just the repetitive demands on the body, it’s come back and we’re going to give him a little extended time to try and nip this for the rest of the year,” said coach Jim Montgomery.

With Forbort out for a good chunk of time, rookie Mason Lohrei was recalled from Providence.

Forbort meanwhile, led the B’s in penalty kill ice time average at 3:34, with Brandon Carlo close behind him at 3:27 for a PK that was leading the league going into Thursday’s game with an 89% kill rate. That will require the remaining left shots to pick up the slack.

“(Hampus Lindholm) will go on the first pairing and (Matt Grzelcyk) has done a really good job here this year, being ready. In practice he’s done a great job of running the right routes and we think he’s going to do a real good job for us, so he’s going to be the second left-shot pairing. And Lohrei has killed some this year, so we’ve got three left shots,” said Montgomery.

Lohrei played 10 games earlier in the season in Boston when Grzelcyk was on LTIR, posting 1-3-4 totals. His offensive talents can jump out at you, but the defensive struggles mounted as the NHL games piled up.

In Providence, he’s got six assists in 10 games.

“He did really well. He was really dominant the first week he was back (in Providence), was not as dominant (last) weekend but still helped the team win some hockey games,” said Montgomery. “We know what he’s done for us this year and how good he’s been. We’re excited to see where he’s at in his development stage and how much he’s going to help us like he did the last time we played Buffalo.”

Lohrei was set to play on a third pair with veteran Kevin Shattenkirk.

He was given a list of things to work on when he went down to Providence.

“Closing hard, just being physical, defensive stuff, playing quick,” said Lohrei. “There’s definitely a speed difference (between AHL and NHL) for sure, but it’s still obviously a really good league down there, too. There are really good players. I just try and focus on my own game and get better every day.”

He was looking forward to playing with Shattenkirk.

“Obviously, he’s played so many games and he’s such a great player. He’s an unbelievable guy to learn from and talk to on the bench. I’ll definitely utilize his knowledge and try to pick his brain, so it’ll be good,” said Lohrei…

There was a surprise guest at the B’s morning skate. With Jeremy Swayman under the weather, the B’s winningest goalie of all time, Tuukka Rask, stepped in between the pipes and took some shots. The retired Rask currently works with the team as an ambassador.

“Tuukka was good out there, wasn’t he? He hasn’t worked out in two years, he said,” said Montgomery with a chuckle.

Said Trent Frederic: “He was good. I didn’t score on him. Shut out twice. 0-for-2. It’s been two years since I scored on him.”

With the B’s keeping Swayman away from the team while he was ill, Brandon Bussi was headed to Boston to back up Linus Ullmark….

After an extremely slow start, Jake DeBrusk is starting to produce, with 4-6-10 totals in 23 games, though Montgomery still thinks he’s got a little way to go before hitting his 2022-23 form.

“He’s a very reliable player. We use him in every situations. I think he might be second on the team in 5-on-5 icetime behind (David Pastrnak) (13:41 at even strength time for DeBrusk), so it shows how much we lean on him and we’re starting to see the production come,” said Montgomery. “And I’ve had a lot of talks with him. I still think his details, his habits aren’t where they were last year, and he’s getting close to there. And as he gets close to where he was last year, I think the production is really going to spike up.”