Grzelcyk took a hard check to the head in the first period of Game 2, and hasn't returned for the second period, Matt Porter of The Boston Globe reports.

EDGE Analysis

Grzelcyk was on the wrong end of an Oscar Sundqvist check from behind at the end of period one, and hasn't returned since. Grzelcyk immediately went down to the ice holding his head and was helped to the locker room. It's unclear if he'll return at some point in the game, but as of now, the Bruins will roll with five defenseman. Connor Clifton could get a bump up to the second-line power play unit as long as Grzelcyk is out.