Hearts defender Aaron Hughes is a major doubt for Northern Ireland's final batch of World Cup qualifying fixtures after limping off injured against Dundee on Saturday afternoon.
The 37-year-old was replaced seven minutes into his side's eventual 2-1 loss at Dens Park due to a slight issue with his calf, which was flagged in the build-up to the match.
"We knew he might struggle with his calf injury," Hearts boss Craig Levein told reporters after the Scottish Premiership clash. "We decided to give him a chance but obviously it didn't last and forced us into the change."
Northern Ireland may now be without their most-capped outfield player for games against Germany and Norway over the next seven days, as he will likely need time to recover.
Michael O'Neill's men are in a strong position on the road to Russia, sitting second in the Group C standings and on the brink of securing a best-placed runners-up berth to reach the playoffs.
