BOSTON (CBS) — When the Bruins hit the ice for Game 3 of the Stanley Cup Final in St. Louis on Saturday night, they’ll need a defenseman to step up in place of the injured Matt Grzelcyk.

The Bruins left for the Midwest on Thursday, but Grzelcyk remained in Boston after taking a crushing hit early in Wednesday night’s Game 2 loss to the Blues. It’s extremely likely we won’t be seeing the 25-year-old again this postseason, leaving a void on Boston’s third defensive pairing alongside Connor Clifton.

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Bruce Cassidy has a pair of veteran D-men to slide into Grzelcyk’s spot in John Moore and Steven Kampfer, and said it will likely be Moore after Friday’s practice. But the final decision won’t come until after Saturday’s morning skate.

Cassidy is leaning toward more Moore because like Grzelcyk, the 28-year-old veteran is a lefty. Moore saw action in four of Boston’s opening round games against the Toronto Maple Leafs, but has watched 14 postseason games due to injury or as a healthy scratch. The last time he saw the ice was in Game 4 of Boston’s Eastern Conference Final sweep of the Carolina Hurricanes, when he played 11:48 in place of the injured Zdeno Chara.

Overall, Moore has played just over 64 minutes this postseason. He’s averaged 12:52 in his five playoff games, and checks in at a minus-4 during his time on the ice. In his 61 games during the regular season, he averaged 18:46 of playing time (good for sixth-most among Boston defensemen) and contributed offensively with four goals and nine assists.

Moore skated with Clifton at Friday’s practice in St. Louis, and said he’s ready if his number is called Saturday night.

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“It comes down to professionalism, how you take care of yourself. It’s easy to get off track this time of year and kick your feet up, but when you’re out, they really do a good job of making sure you’re accountable and put you through the ringer, making sure your conditioning is where it needs to be,” Moore said after Friday’s practice. “We’ve had this situation before, but the group has been amazing in terms of support and that ‘Next Man Up’ mentality.”

Meanwhile, Kampfer has only played in two games this postseason. He scored a goal in Game 1 against the Hurricanes, playing nearly 15 minutes in place of a suspended Charlie McAvoy. He was mostly used to kill penalties in his only other postseason appearance, which came in the opening round against Toronto. In 35 regular season games, Kampfer checked in as a minus-6 with three goals and three assists.

Cassidy went to Kampfer the last time the Bruins needed a fill-in blue liner, but going with the left-handed Moore wouldn’t force him to shuffle his other defensive pairings.

Boston’s defense went through plenty of shuffling throughout the regular season though, with McAvoy, Chara and Kevan Miller all missing chunks of time. Cassidy believes that will help, no matter who he inserts into the lineup this weekend.

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“The partner chemistry this year, as a result of a lot of guys getting out of the lineup, that part I think we can overcome,” the B’s head coach said after Game 2. “Guys are used to playing with different guys.”