Bruins coach Bruce Cassidy says he doesn't know if Zdeno Chara will play in Game 5 after he took a puck to the face. (0:42)

ST. LOUIS -- Bruins coach Bruce Cassidy said injured defenseman Zdeno Chara will be evaluated in Boston and the team is preparing in case he can't go in Game 5.

Chara took a puck to the face in the second period of the Bruins' Game 4 loss to the St. Louis Blues on Monday and, according to multiple reports, has a broken jaw. He dropped to the ice bleeding and was helped to the locker room. Chara returned with a face shield and sat on the Boston bench for the third period but did not play, per team trainers' orders.

Forward Brad Marchand wasn't surprised to see the team captain on the bench.

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"He's an absolute warrior. If it wasn't for a doctor, he would have played that game. He's that kind of guy who you're going to have to kill him to keep him off," Marchand said Tuesday. "He's an absolute leader, and those things, you just gain respect for him every single day with what he's willing to go through to be part of the group and lead this team. He's an incredible person."

Through 20 playoff games, Chara has a goal and four assists with a plus-12. He played over 24 minutes in Games 2 and 3 but was limited to just 8:23 in Game 4, though he did pick up an assist on Charlie Coyle's goal.

If Chara can't go in Game 5, Cassidy said it could have a domino effect on the Bruins' lineup. Boston has been without defenseman Matt Grzelcyk since Game 2, when he took a hit from behind from Blues forward Oskar Sundqvist, who was subsequently suspended for one game. Grzelcyk didn't travel to St. Louis for the last two games and has been in the concussion protocol.

Cassidy said there's a possibility that if both can't go in Game 5, the Bruins could play seven defensemen and 11 forwards. Among the defensemen who are in the mix to be added to the lineup: veteran Steve Kampfer, who has played in two games for Boston in this postseason; Jeremy Lauzon, a 22-year-old who played 16 games in the regular season for Boston; and Urho Vaakanainen, a 20-year-old who played two games in the regular season for Boston.

"There are different things you gotta do to support each guy missing. Gryz is more of a puck mover. How are we going to move the puck better when he's out of the lineup? Well, your forwards have to support the puck better," said Cassidy. "This matchup is not good with Zee out, let's face it. They're a big, heavy team, so we lose that element. But someone else is going to have to step up, and I think we do it as a group."

If the Bruins play seven defensemen, it could affect how Cassidy approaches his forward group. He said he is considering a shakeup of lines, in particular to get their second line with David Krejci going. The Bruins center doesn't have a point in the series.

"We've moved [David Pastrnak] in there periodically for a few shifts here and there. We have to sit down and they have to change the way they're playing. It hasn't worked so far to generate offense," said Cassidy, who cautioned that changing the makeup on one line could affect the chemistry of other lines that are affected. "Problem with that this time of year is you're so far down the line, the other lines have their chemistry. Especially our bottom two lines."

Chara's status is up in the air, but it's clear the Bruins are keeping their options open. Cassidy cautioned to never count an injured player out at this stage of the postseason.

"It's the Stanley Cup. I suspect for every player, it's to get their name on the Stanley Cup and not let their teammates down," said Cassidy.