The Boston Bruins have been dealt a serious blow.

According to an update released by the team earlier today, top line defender Charlie McAvoy, who left last Saturday's overtime win over Montreal just 17 seconds into the game, has suffered a left MCL sprain.

The injury will keep the young stud out at least a month and now throws one of the hottest teams in hockey into an interesting situation down the stretch.

As confirmed yesterday by Bruins head coach Bruce Cassidy, the B's will turn to Brandon Carlo to join captain Zdeno Chara on the first line.

Carlo has performed well this season and should be able to fill in for McAvoy in the short-term. An extended stint on the front line could hurt the team's play as they vie for playoff positioning.