From a report at the Penguins morning gameday skate from the PG's Shelly Anderson:
Everyone other than D Matt Niskanen on the ice for #Penguins morning skate at CEC....Simon Despres seems to be getting a lot of reps with Kris Letang at #Penguins morning skate.
It looks like Niskanen will be out for tonight's game. Niskanen was injured taking a nasty spill legs first into the boards in the first period of last game versus Ottawa. He did not return and was said to have a "lower body injury". There were no updates yesterday, when the Penguins had the day off. Dan Bylsma may speak to Niskanen's condition later on today, but in true NHL fashion, his leg could be hanging by a strand and he'd probably be considered "day-to-day".
Depres has been a healthy scratch the past two games, the Penguins also have defenseman Robert Bortuzzo, who has been a healthy scratch all season on the roster. One of those two (like Despres) would join Kris Letang, Brooks Orpik, Paul Martin, Deryk Engelland and Ben Lovejoy as the defensemen in the lineup for tonight's game.