Charlie Mulgrew went off injured as Scotland kept their World Cup qualification hopes alive with a 2-0 victory over Malta.
The Rovers skipper, who started the game at Hampden Park, was replaced by former club captain Grant Hanley on 56 minutes.
The concerning news comes on the same day fellow Rovers defender Darragh Lenihan underwent an operation on a fractured foot, which is expected to keep him out for several months.
Christophe Berra opened the scoring for the Scots, heading home Leigh Griffiths' corner on nine minutes, before Griffiths made the points safe early in the second half, knocking in the rebound after James Morrison's shot had hit the post.
The victory moved Scotland to within a point of second-placed Slovakia, who lost 2-1 away to England, with two group games remaining.
Gordon Strachan's side take on Slovakia and Slovenia in their final Group F fixtures next month.
In Belfast, Corry Evans put in an impressive 90-minute performance as Northern Ireland secured second spot in Group C courtesy of a 2-0 victory over the Czech Republic - their fifth straight win.
The Rovers midfielder was recalled to the starting line-up, having featured for the final 12 minutes of Friday's 3-0 victory over San Marino.
Corry's brother Jonny headed the hosts in front on 28 minutes, before his West Brom team-mate Chris Brunt fired home a fantastic free-kick just before the break.
The victory puts Michael O'Neill's men in a promising position to progress to the November play-offs, with the best eight of the nine group runners-up making the play-offs.
Northern Ireland sit second on 19 points from eight games, five points behind Germany, who they face next at Windsor Park on October 5th.