Ottawa Senators head coach DJ Smith said forward Derek Stepan is week-to-week with an upper-body injury but it "doesn't look promising."
Stepan left Tuesday's shootout win over the Montreal Canadiens in the first period and did not return.
The 30-year-old has one goal and six points in 20 games with the Senators this season, his first with the team.
Acquired by the Senators in December from the Arizona Coyotes for a second-round pick, Stepan carries a $6.5 million cap hit in the final season of his current deal.
Smith also said goalie Marcus Hogberg remains out and hasn't skated since his injury.
Hogberg left a game last week against the Toronto Maple Leafs in the first period with an undisclosed lower-body injury.