Town skipper Gareth McAuley appeared to pull a hamstring as his Northern Ireland side defeated San Marino 4-0 in Belfast on Wednesday evening. McAuley, playing at right-back, limped off on the hour mark.
The Blues central defender, who was winning his 13th full cap, had been booked in the first half for a foul as his side cantered to an easy victory.
Town have recently had a spate of injuries to defenders with Ben Thatcher still out for around a month with a torn thigh muscle, Moritz Volz hurting a hamstring, Pim Balkestein injuring his groin and Alex Bruce picking up a similar problem while away with the Republic of Ireland.
Thatcher remains on the sidelines, but Volz returned to action at Charlton, Balkestein was back in the reserves on Tuesday and Bruce is expected to be OK for Saturday's home game with Swansea.
Balkestein replaced McAuley at Southampton last month when the Northern Irishman was out with a dead leg and appears to be his most likely deputy should the former Leicester man be unavailable for Saturday's game.
Elsewhere, Veliche Shumulikoski played the full 90 minutes as Macedonia lost 1-0 to an Iceland side featuring Hermann Hreidarsson in Reykjavik.
Meanwhile, Alan Quinn says he wants to return to the Republic of Ireland side, having previously won six caps: "It's up to me to keep playing well for Ipswich and it's always nice to play for your country and hopefully I'll impress someone if my form continues to improve.â€Â