Dundee United striker Billy McKay has been called into the Northern Ireland squad as a replacement for the injured Ben Reeves.
MK Dons midfielder Reeves is being treated at his club for an unspecified injury and will miss the forthcoming European Qualifiers against the Faroe Islands and Hungary.
McKay, who recently joined the Tannadice side on loan from Wigan, takes Reeves' place with boss Michael O'Neill having concerns over a couple of other squad members.
Nottingham Forest forward Jamie Ward (hamstring) is yet to link up with the squad, but O'Neill is more positive about Chris Brunt's chances after he was injured while playing for West Brom.
O'Neill said: "Chris Brunt is working separately with the medical team but we're optimistic rather than pessimistic about his chances of being involved on Friday night [in the Faroes].
"Jamie Ward we've left at Forest for the time being, we'll basically asses that on a day by day basis but Jamie, realistically, has the least chance of making it.
"Ben Reeves unfortunately has withdrawn and we've added Billy McKay."
O'Neill's men go into the next rounds of fixtures in second place in Group F, behind Romania by one point and two points clear of third-placed Hungary, who they face next Monday at Windsor Park. Hungary meet Romania in a vital game on Friday.