Northern Ireland's most capped outfield player Aaron Hughes will miss this week's World Cup qualifiers against Germany and Norway through injury.
The 108-cap defender, 37, came off just seven minutes into Hearts' defeat to Dundee at the weekend with a calf problem he had been struggling with before the game.
Hughes met up with the rest of Michael O'Neill's squad in Belfast but did not train on Monday and a day later it was confirmed he would not be available to face the Germans on Thursday or the Norwegians on Sunday.
A tweet from Northern Ireland's official Twitter account said: "UPDATE | Aaron Hughes out of @FIFAWorldCup qualifiers against Germany & Norway. Callum Morris called up. #GAWA"
Hughes had appeared in his team's past three qualifiers, during which time they did not concede, and he has also featured in both of Northern Ireland's games against Germany over the past 16 months.
Had he played against the world champions in Belfast on Thursday, 20 years on from his maiden international call-up, he would have surpassed Bobby Moore to become the most capped defender ever for the four home nations.
Beyond West Brom duo Gareth McAuley and Jonny Evans, O'Neill's only obvious central-defensive options are the trio of Tom Flanagan, Adam Thompson and Morris - none of whom have made a competitive appearance for their country.
It means he is likely to play four at the back rather than five on Thursday, and it puts even more importance on Evans not picking up a caution that would ensure he was suspended to face Norway in Oslo in their final qualifier.
Northern Ireland have guaranteed second place in Group C but only eight of the nine group runners-up will be in November's play-offs.