Wigan boss Roberto Martinez fears Gary Caldwell faces a lengthy spell on the sidelines through injury.
Caldwell suffered a fractured cheekbone during the 2-2 draw at West Brom, but bravely completed the full game at The Hawthorns.
Martinez admits it will be a major blow to lose their skipper as they battle to avoid relegation from the Premier League.
"Gary Caldwell had a fractured cheekbone and that is the biggest negative we picked up," said Martinez.
"He is a true captain and a great leader and we are going to miss him.
"We are going to assess him in the next 24 hours but it is not really good news."
Martinez is also sweating over the fitness of full-back Maynor Figueroa after he picked up a hamstring injury against West Brom.
"Maynor has a hamstring injury and we are going to assess him in the next 24 hours," added Martinez.
Statement of intentMeanwhile, Martinez believes Wigan have "shown a bit of a statement" by keeping hold of Charles N'Zogbia during the transfer window.
Newcastle are believed to have made a last-ditch effort to land N'Zogbia before the transfer window slammed shut on Monday night, but Wigan rejected their overtures.
N'Zogbia impressed during the draw with West Brom and Martinez is delighted to have kept the Frenchman.
"Our intention this window was to finish with a stronger squad," noted Martinez.
"We had two major objectives, getting all the players back from injury, and we didn't want to lose any of the prize assets. We managed to do that.
"In the past, the fans have been a bit disappointed at losing players at the wrong time. Everyone is proud that Wigan showed a bit of a statement by keeping the players for the important challenges we have at the moment."