BOSTON -- If the Boston Bruins are worried about the prospect of playing a pivotal Game 5 of the Stanley Cup Final without their captain, veteran defenseman Zdeno Chara, they aren't showing it.

The Bruins have been here before, both in the regular season and playoffs. And coach Bruce Cassidy expects them to be on their game -- with or without Chara -- as they host the St. Louis Blues on Thursday with the best-of-seven series tied at two games apiece.

"I think our guys are good knowing that the team will pull together," Cassidy said. "In this particular series, against a heavier team, that's where you miss what (Chara) brings to the table. In terms of the mentality, I think this team will be OK."

Cassidy remained relatively mum when speaking with reporters about the facial injury (a reported broken jaw) Chara sustained in the Bruins' Game 4 loss at St. Louis. The 42-year-old didn't skate Wednesday, and an update on his availability is expected early Thursday.

"We don't know right now," Cassidy said. "There's a little bit of that hope factor for us as well."

The Bruins could receive a defensive boost if Matt Grzelcyk, sidelined since entering concussion protocol following a vicious hit from Blues forward Oskar Sundqvist in Game 2, is able to return to the lineup. Grzelcyk was back at practice in a non-contact jersey Wednesday, though his status also was a question mark.

"I'm just happy to be back around the guys, and I feel a lot more like myself," he said. "Hopefully I can play. If I get called, I'll be ready."

If Monday's Game 4 was any indication, Grzelcyk will need to be on his game if he does play. The Blues feasted on the Bruins' defense following Chara's exit in the second period of their 4-2 win, outshooting the Bruins 13-4 in scoring two goals in the third period to knot the series.

"We're feeling like we're getting momentum in the game," said Blues forward Vladimir Tarasenko, who has six goals and three assists in his past eight contests. "All lines doing it shift after shift, it gives a team a lot of confidence and gives us a boost."

Though Chara is questionable, St. Louis doesn't intend to change its game plan. Teams that have won Game 5 when the Stanley Cup Final is tied at two apiece have won the series 72 percent of the time, underscoring the importance of Thursday's contest.

"I don't think the preparation changes if he plays or he doesn't play," Blues coach Craig Berube said. "We just got to be ready to go no matter if he's in or out. That team over there is very good. They're going to be hungry and desperate. We've got to come with that desperation and hunger, too."

The Blues will make a change on defense for Game 5, subbing in Robert Bortuzzo for Joel Edmundson. Bortuzzo sat in Game 4 with Vince Dunn returning from injury.

Tuukka Rask returns to net for Boston after allowing three goals for the second time in three games in the Monday loss. Rask, who has a 1.96 goals-against average and a .938 save percentage this year's playoffs, said his style of play won't change much regardless of who is playing in front of him on defense.

"If I start yelling too much and directing traffic, it's a waste of energy," he said. "I just try to mostly focus on stopping the puck. If I see something, I say something."

On the other side, Blues goaltender Jordan Binnington (2.52 GAA, .909 save percentage in the postseason) is one win shy of matching the NHL rookie record for most by a goalie in a single postseason (15).