Grzelcyk (concussion) hasn't gained medical clearance, and won't play in Sunday's Game 6 in St. Louis, Matt Porter of The Boston Globe reports.

EDGE Analysis

The 25-year-old has missed the last three games of the series after he was knocked out of Game 2 on a hit from Oscar Sundqvist. Even though Grzelcyk was sporting a non-contact jersey during Saturday's practice, he won't be available for Sunday's contest. In his stead, the Bruins will go back to six defensemen in their lineup, with Steve Kampfer the odd man out.