ST. LOUIS -- David Backes and Matt Grzelcyk will remain out for the Boston Bruins for Game 6 of the Stanley Cup Final against the St. Louis Blues at Enterprise Center on Sunday (8 p.m. ET; NBC, CBC, SN, TVAS).
Backes, the former Blues captain, will be a healthy scratch for the second straight game. Grzelcyk, a defenseman, remains in the NHL concussion protocol and has yet to be cleared medically to play.
The Bruins trail 3-2 and need a win to force Game 7 at Boston on Wednesday and prevent the Blues from winning the Stanley Cup for the first time.
[RELATED: Complete Stanley Cup Final coverage]
After dressing seven defensemen and 11 forwards in a 2-1 loss in Game 5 on Thursday, the Bruins will go back to six defensemen and 12 forwards, but coach Bruce Cassidy decided to play rookie forward Karson Kuhlman instead of Backes.
Kuhlman, who has two assists in six Stanley Cup Playoff games, has been a healthy scratch for 12 straight games since last playing in Game 3 of the Eastern Conference Second Round against the Columbus Blue Jackets.
"He's got a good motor," Cassidy said. "That's what we've liked about him. … He's good on the walls. He's quick, good forecheck motor. The challenge for him will be like a lot of our guys, getting inside on this big, heavy D. But he is fast and he's responsible."
Cassidy said Kuhlman will be with Jake DeBrusk and David Krejci on the second line, where he played earlier in the playoffs.
Video: STL@BOS, Gm5: DeBrusk buries one-timer from circle
"He can make some of those small-area plays," Cassidy said. "[Backes] is a little more straight forward, chip and chase, get behind. We always felt David played his best hockey [on the fourth line]. It's just we've got [Noel] Acciari there. We've had [Chris] Wagner there. There's only so many roles, I guess, carved out on our team for that style. And David's been fine. He's matched up physically well against this team.
"It's just a decision we've made to be a little different. Maybe [Krejci] sees a few more pucks in the neutral zone and in that case get a little more speed off the rush or speed on the original forecheck. We'll see how it plays out."
Backes, who has five points (two goals three assists) in 15 playoff games, said Saturday he was prepared to sit out again if that was what Cassidy decided.
"We're here to win," Backes said. "If my part's grabbing the pom-poms again, I'll shake those things until all the frills fall out of them."
Kuhlman, who had five points (three goals, two assists) in 11 regular-season games with Boston, said Cassidy told him Saturday there was a chance he might play in Game 6 and confirmed it Sunday morning.
"Obviously, it's been a dream since you're a little kid to play in the Cup Final," Kuhlman said. "I've just got to do everything I can to help this team win. … We know what I need to do to help this team and that's all I can try to do. Not try to be a superhero tonight and just do my job."
Video: BOS@CBJ: Kuhlman slams home loose puck
Grzelcyk, who has seven points (three goals, four assists) in 19 Stanley Cup Playoff games, participated in the Bruins' optional morning skate Sunday after practicing Saturday wearing a maroon non-contact jersey. He hasn't played since being injured on a hit from Blues forward Oskar Sundqvist in Game 2 on May 29. Sundqvist received a boarding penalty and was suspended for Game 3 for the hit.
Wagner, who hasn't played since blocking a shot with his right arm in Game 3 of the Eastern Conference Final against the Carolina Hurricanes on May 14, skated for the second straight day. Cassidy said Saturday that Wagner might be available to play in Game 7, if there is one.