By Michael Hurley, CBS Boston

BOSTON (CBS) — One of the toughest players in the NHL, Zdeno Chara does not often go down to the ice in pain. It takes quite a bit to get the Bruins captain to hit the deck.

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That was what happened just minutes into Game 4 of the Stanley Cup Final on Monday night, in a scene that left a bloodied Chara heading directly to the Bruins’ dressing room for repairs. And now, the Bruins aren’t sure if they’ll have their captain going forward.

Chara ended up injured after getting his own stick on a shot by Brayden Schenn. Chara succeeded in the shot block but redirected the puck right up into his own face.

Chara immediately fell to the ice, removing his gloves, indicating the seriousness of the pain.

After the whistle blew, trainers tended to Chara, who was bleeding from his mouth.

The Blues were leading, 2-1, at the time of Chara’s injury. Chara had picked up an assist in the first period, his fifth point of the postseason.

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The 42-year-old captain missed Game 4 of the conference finals with an undisclosed injury but has otherwise been a reliable presence all postseason long for Boston. He entered Game 4 averaging 22:39 time on ice per game.

Chara did not return to the ice for the remainder of the second period, but he did return to the bench in the third period, wearing a full face shield. He did not, however, take any shifts in the third period.

Defenseman Brandon Carlo said that Chara could “barely talk” while on the bench.

“Just shows his great leadership. He’s there to support the guys,” Carlo said. “Obviously his mouth has some blood and I don’t know what’s going on there. But he can barely talk and he’s out there supporting us, so just his leadership is on a whole other level, especially during this final round. He’s always there for us, he’s been great communicating, and just wants to be there as a support valve.”

Bruins head coach Bruce Cassidy said he does not know if Chara will be available to play Thursday night in Game 5.

Chara’s injury marked the second time the Bruins lost a defenseman during a game in this series, both of which ended in losses for Boston.

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If Chara cannot play in Game 5, Cassidy named Steven Kampfer, Urho Vaakanainen, Jakub Zboril and Jeremy Lauzon as potential options to fill in. Kampfer has two career playoff games of experience, while the other three players have just 20 combined regular-season games — and zero playoff games — of experience. Monday night was the 179th playoff game of Chara’s career.