Krug (undisclosed) exited Game 4 against the Lightning on Friday after taking a hard hit into the boards, Amalie Benjamin of NHL.com reports.

EDGE Analysis

The 27-year-old looked to be in extreme pain, but he was able to help the Bruins break it out of the zone before heading directly down the tunnel. Krug has been remarkable this postseason, posting three goals and 11 points, including an assist in Friday's game. Therefore, a loss of Krug would be catastrophic to the Bruins' blue line as well as their power play.