Chara (facial injury) and Grzelcyk (concussion protocol) each took part in the morning skate and will be a game-time decision, Bruins coach Bruce Cassidy said.
Video: News and notes ahead of Game 5 of the SCF
"We'll see how they feel at 7 or so tonight," Cassidy said.
Chara was injured when a shot by Blues forward Brayden Schenn ricocheted off his stick and hit him in the face at 3:07 of the second period of Game 4 at Enterprise Center on Monday. He didn't play another shift in the Blues' 4-2 win that evened the best-of-7 series.
Chara didn't practice Wednesday but was on the ice wearing a clear jaw protector attached to his helmet at the morning skate.
"At this time of the playoffs, everyone has injuries and there are challenges that you have to overcome to play," Chara wrote in an emailed statement to the media. "I'm no different than any player on either team."
Grzelcyk missed Games 3 and 4 after sustaining a concussion on a hit from Blues center Oskar Sundqvist in the first period of Game 2. He has to be medically cleared to play.
The Bruins are 5-1 after a loss in the Stanley Cup Playoffs. The Blues went 6-1 in Games 5-7 in three Western Conference series.
Since 1939, when the NHL went to the best-of-7 format, when the Cup Final is tied 2-2, the winner of Game 5 has gone on to win the Stanley Cup 18 of 25 times (72.0 percent).
Here are 5 keys to Game 5:
[RELATED: Complete Stanley Cup Final coverage]
1. Lineup options for Bruins
Boston is considering playing seven defensemen.
If Chara and Grzelcyk play and the Bruins want to use seven, John Moore would remain in and David Backes could be the forward who comes out. Steven Kampfer would play if either Chara or Grzelcyk can't and Boston still wants to use seven defensemen.
If neither Chara nor Grzelcyk play, it's likely the Bruins will go with six defensemen, using Kampfer and Moore along with Brandon Carlo, Torey Krug, Charlie McAvoy and Connor Clifton.
Cassidy said right wing David Pastrnak and left wing Marcus Johansson would be the likely options to double shift in the event the Bruins have 11 forwards in the lineup because neither kills penalties.
2. Attacking Boston's D
The Blues have to see if they can take advantage of the Bruins defensemen early in the game.
Putting the puck behind them and forcing them to turn and take hits to make plays will make their minutes earlier in the game difficult, which would create a challenge for them later, especially if the Bruins feel the need to protect some of their defensemen because of injuries they might be playing with.
"That's our game," Blues coach Craig Berube said. "That's when we're successful, so we've got to do it no matter what. We expect [Chara and Grzelcyk] to play. That's the way we look at it. Either way that's our game, that's how we've got to have success or we will have success."
3. Blues need power-play goal
The Blues are 1-for-13 with 21 shots on goal on the power play in the series. They haven't generated much momentum with the man-advantage and allowed a shorthanded goal in Game 4.
Perhaps with defenseman Vince Dunn back and into the series after playing in Game 4, the Blues can make the adjustments they need on the power play to generate better scoring chances. Dunn had three of his nine shot attempts in Game 4 on the power play.
4. Bruins could use spark from Krejci line
The Bruins have gotten a combined two points from center David Krejci's line, two assists on the power play from left wing Jake DeBrusk. The line, which has included Backes at right wing, has 14 shots on goal in the series.
Backes could be scratched from Game 5, meaning Pastrnak likely would get some time with Krejci and DeBrusk. Perhaps he can help them have more of an attack-and-shoot mentality, which has been a problem, according to Cassidy and DeBrusk.
5. Boston's 5-on-5 production
It's not just the second line that hasn't contributed at 5-on-5. The Bruins have zero 5-on-5 goals from their top line of Patrice Bergeron, Brad Marchand and Pastrnak.
Boston has scored six of its 15 goals in 5-on-5 situations. Asked how the Bruins could do more at 5-on-5, Cassidy delivered an answer that was 90 seconds in length and required more than 300 words. That gives you an idea of how many issues they're having.
The Bruins need to get inside the Blues defense more often and get more shots to the net through the traffic. They had 19 shots on goal at even strength in Game 4. An odd-man rush would help, but it's not guaranteed, so the Bruins need clean breakouts and a shot mentality.
Blues projected lineup
Jaden Schwartz -- Brayden Schenn -- Vladimir Tarasenko
Zach Sanford -- Ryan O'Reilly -- David Perron
Pat Maroon -- Tyler Bozak -- Sammy Blais
Ivan Barbashev -- Oskar Sundqvist -- Alexander Steen
Carl Gunnarsson -- Alex Pietrangelo
Jay Bouwmeester -- Colton Parayko
Vince Dunn -- Robert Bortuzzo
Scratched: Joel Edmundson, Robby Fabbri, Michael Del Zotto, Mackenzie MacEachern, Chris Thorburn , Ville Husso
Injured: Robert Thomas (undisclosed)
Bruins projected lineup
Brad Marchand -- Patrice Bergeron -- David Pastrnak
Jake DeBrusk -- David Krejci
Marcus Johansson -- Charlie Coyle -- Danton Heinen
Joakim Nordstrom -- Sean Kuraly -- Noel Acciari
Zdeno Chara -- Charlie McAvoy
Torey Krug -- Brandon Carlo
Matt Grzelcyk -- Connor Clifton
Scratched: Steven Kampfer, Karson Kuhlman, David Backes
Injured: Chris Wagner (concussion protocol), Kevan Miller (lower body)
Bortuzzo will return to the lineup after being scratched for Game 4, replacing Edmundson. … If Backes is scratched, it will be his first time out of the lineup since Game 3 of the Eastern Conference Second Round against the Columbus Blue Jackets, which was his fifth straight game as a healthy scratch.
Listen: New episode of NHL Fantasy on Ice podcast