BEDFORD, Mass. -- All season, the depth of the Boston Bruins' defense has been challenged, the team having to dig deep into its prospect pool, into the American Hockey League, unearthing names that might never have been expected to play a role.
That's how Connor Clifton ended up as a regular on the third pairing throughout the Stanley Cup Playoffs.
But this is likely to be the biggest test yet for the Bruins.
With Zdeno Chara and Matt Grzelcyk -- not to mention Kevan Miller, out the entirety of the playoffs -- potentially unavailable for Game 5 of the Stanley Cup Final against the St. Louis Blues at TD Garden on Thursday (8 p.m. ET; NBC, CBC, SN, TVAS), the Bruins are contemplating not only going with an 11-forward, seven-defensemen lineup, but dipping into the "Black Aces" -- players from Providence of the AHL mainly here to soak in this playoff experience -- to fill out the roster.
[RELATED: Complete Stanley Cup Final coverage | Chara status uncertain for Bruins in Game 5]
It's not exactly something coach Bruce Cassidy relishes, especially not in this best-of-7 series that's tied 2-2. Still, it's a way to survive without the team's biggest -- literally and figuratively -- defenseman unavailable, should that be the case.
"It's not easy, but it's the hand we've been dealt if both those guys are out," Cassidy said, after the Bruins landed at Hanscom Air Force Base on Tuesday. "Who gives us the best chance to win? Do we need to dress seven [defensemen] because we've got a little bit of inexperience back there? And how does that affect our forward group if we'd have to take a guy out?
"So, it's not an easy decision. It's not one I want to make. I hope that our D are healthy but, again, you have to do what you've got to do."
There was no update about Chara's ability to play in Game 5 after the Bruins arrived in Boston shortly after 2 p.m. ET on Tuesday, with the defenseman headed off to the doctor. He was hit in the face with a puck at 3:07 of the second period in Game 4, a 4-2 loss, and never returned to the ice, though he sat on the bench with his teammates in the third period wearing a full face shield. Grzelcyk got a concussion in Game 2 and hasn't played since.
The Bruins have one practice and morning skate before Game 5 to determine who might play and how to deploy a lineup with 11 forwards and seven defensemen, should they go in that direction.
If so, as Cassidy said, it would entail one forward being double shifted -- potentially David Pastrnak -- predominantly at 5-on-5. But there are some caveats that would need to be kept in mind for that type of an arrangement.
"When you take out a forward, you've got to be careful that it doesn't affect one of your special teams or, if it does, what's your Plan B?" he said. "How it affects the D is … sometimes it just might be which guy is going better that night, as simple as that, who is up to the challenge that particular night."
Video: Adjustment suggestions for Bruins ahead of Game 5
Steven Kampfer could be the first defenseman to be called upon if Grzelcyk and Chara remain out, though he is a right-shot defenseman; Grzelcyk and Chara shoot left-handed. Two other options are Urho Vaakanainen and Jeremy Lauzon, prospects who were pressed into duty earlier this season, and left shots. Vaakanainen got a concussion in his second NHL game, played back in October. He never returned. Lauzon, meanwhile, played 16 games this season while the Bruins went through various injuries.
"If it's a newer 'Black Ace' [who comes in the lineup], we'd have to see how they respond," Cassidy said. "So, some of it would be on the fly, see how they play. Some of it would be looked at ahead of time; who's the best penalty killer, because some of [Chara's] best work is done there."
In that case, John Moore would step into some of Chara's role on the penalty kill, inheriting some of his minutes. Meanwhile, former Blues captain David Backes could be vulnerable to a seat in the press box if, indeed, Cassidy decides to sacrifice one of his forwards.
But whatever the Bruins decide to do, if Chara and Grzelcyk are out for Game 5, it will be a tremendous hole that the Bruins will have to fill. It won't be any one or two players stepping in. It will be the entire defense, the forwards, the team as a whole. That's what they've done to get through all their injuries on defense all season, and it's what they would have to do in Game 5 and, potentially, beyond.
"We can all play with each other," defenseman Charlie McAvoy said. "We all complement each other well. We all trust each other a lot. You just believe in your guys and you know that the guy, whoever's out there, is going to get the job done. So, whoever is slotted in for this next game -- I don't know how everything is going to shake out -- but we believe in each other and we believe we can get the job done."
Listen: New episode of NHL Fantasy on Ice podcast