Michael Hart is likely to be sidelined for what Hibernian describe as "a lengthy period" after picking up an injury against Sunderland.
The right-back suffered what the club believe to be a serious groin injury during Saturday's friendly, which finished 0-0 at Easter Road.
Hart, 31, was forced to come off the pitch five minutes into the match.
Midfielder David Wotherspoon suffered a slight ankle injury but is expected to be fit for Scotland Under-21 duty.
Hibs say he will meet up with the national squad ahead of Wednesday's friendly against Norway at St Mirren Park.