The Senators official Twitter feed updated during the third period saying that Karlsson's left achilles was cut and he will require surgery. He is out indefinitely.
The Sens were actually pretty solid through 40 minutes but the injury seemed to throw them off. The Penguins scored a couple goals early in the third and coasted to a 4-2 win.
With regards to the play on which Karlsson was hurt...
I won't debate whether or not it was a "dirty" play. It was a bizarre play and I see no need for Cooke's skate to be where it was and it's really difficult to judge intent in a video. I do know that up until he became a "clean" player last season, Matt Cooke was one of the most hated, notoriously cheap players in the NHL. I guess we'll leave it at that.
Losing Erik Karlsson is obviously crippling for this team.
Everything runs through him right now and with Jason Spezza already out until at least April, this is just a ridiculous twist of misfortune for the Senators. It is a loss that hurts the Senators and really the NHL in general. There was no more entertaining player in the league right now. Just brutal.
To add to a rough night for Ottawa, Milan Michalek actually suffered a lower body injury in the warm up and did not play.
Couple days off for the Senators with their next game coming Saturday in Toronto.