The injuries won’t stop mounting for the Boston Bruins, and in turn, the lineups keep getting wonkier.

The B’s are in Toronto on Friday for an Original Six matchup with the Maple Leafs at Scotiabank Arena. It’s the first leg of a back-to-back for the Bruins, concluding Saturday night at TD Garden against the Washington Capitals.

Zach Senyshyn is out roughly four weeks with a lower-body injury sustained in Tuesday’s meltdown against the Florida Panthers, so Boston recalled Trent Frederic from the AHL as a result. The hefty forward, who typically plays as a center, is expected to skate on the left side of the third line opposite Danton Heinen with Par Lindholm in the middle.

With Heinen back on the third unit, Anders Bjork hops up to the second line with David Krejci and Charlie Coyle. Usually, Coyle serves as the third-line center, but absences have forced head coach Bruce Cassidy to use the vet on the right wing next Krejci lately. Although Heinen is a left shot, the Bruins have been left with pretty much no choice than to put him on the right, otherwise they’d be putting either Bjork or Frederic, also southpaws, on their off side.

“The hand we’ve been dealt right now is we have a lot of right wingers out,” Cassidy following Thursday’s practice, via Bruins.com. “We’ve talked about Anders staying on the left side. We don’t want to mess with that, he’s played well there. We want to keep him on the left side. That means Danton has to move, whose played the right side.

“I’ve talked about it before, the other thing I like about (Heinen) is he can move around. He’s got a good hockey IQ, he can figure out what a line needs and fit in. He’s done it on every line on this team.”

Added Cassidy about Frederic: “We’re not gonna bring him up as a left shot and throw him on the right wing, I think that’s a little unfair. We’re already kind of moving him to begin with to see where he’s at.”

Torey Krug remains out, so Matt Grzelcyk stays on the second defensive pairing with Brandon Carlo, while Urho Vaakanainen and Connor Clifton will again form the third pairing.

All told, the Bruins are without Krug, Senyshyn, Jake DeBrusk, David Backes, Brett Ritchie, Karson Kuhlman, Kevan Miller and John Moore, with Cassidy indicating that all those players also will be out Saturday with the exception of maybe Ritchie.

Mitch Marner and Alexander Kerfoot are sidelined for Toronto.

Tuukka Rask will be in net for the Bruins, with Frederik Andersen expected to get the nod for the hosts.

Here are the projected lineups for both teams:

BOSTON BRUINS (11-3-4)
Brad Marchand–Patrice Bergeron–David Pastrnak
Anders Bjork–David Krejci–Charlie Coyle
Trent Frederic–Par Lindholm–Danton Heinen
Joakim Nordstrom–Sean Kuraly–Chris Wagner

Zdeno Chara–Charlie McAvoy
Matt Grzelcyk–Brandon Carlo
Urho Vaakanainen–Connor Clifton

Tuukka Rask

TORONTO MAPLE LEAFS (9-7-4)
Andreas Johnsson–Auston Matthews–William Nylander
Zach Hyman–John Tavares–Kasperi Kapanen
Ilya Mikheyev–Jason Spezza–Trevor Moore
Nic Petan–Nicholas Shore–Frederik Gauthier

Morgan Rielly–Cody Ceci
Jake Muzzin–Tyson Barrie
Travis Dermott–Justin Holl

Frederik Andersen

Thumbnail photo via Nick Turchiaro/USA TODAY Sports Images