Norwich City defender Elliott Ward has suffered a setback in his recovery from a knee injury.
Ward, 26, has been sidelined since the summer, when it was expected he would be out for weeks rather than months.
But the centre-half, who played 41 times last term, could undergo surgery if he does not respond to treatment.
"Wardy's got a little bit of a problem at the minute which we're trying to get to the bottom of," boss Paul Lambert told BBC Look East.
The Canaries have been boosted by the news that centre-halves Zak Whitbread and Daniel Ayala have returned to training and are nearing full fitness.
Lambert is down to two recognised central defenders - in Leon Barnett and Ritchie de Laet - and has been using full-back Russell Martin at the heart of his defence.
But he will not be looking to increase his options in that area in January.
"Not if the three of them are fine," said Lambert. "It's not one of the positions I think might need strengthening.
"Because if we get them back, hopefully we'll be OK."