Gregor (lower body) will be out for a while after suffering the injury in Thursday's game against the Sabres, Bruce Garrioch of Postmedia reports.
Gregor sustained the injury during the second period and was unable to finish the contest. The Senators were already thin at forward with both of Michael Amadio (concussion) and David Perron (back) out, so don't be surprised if Gregor lands on injured reserve to free up a roster spot for another forward. Jan Jenik was recently in the NHL and made one appearance in a fourth-line role, so he could be a leading candidate for a recall.