Owls head coach Stuart Gray issued an injury update following the 1-1 draw with Charlton on Saturday.
Joe Mattock was stretchered off in the first half and Gray said the defender was in serious pain – although it is too soon to determine the severity of the injury.
He said: “It looked a bad one because Joe is an honest boy and when he starts hitting the floor like that, you know he has a problem.
“I’ve just come straight out here to speak to the media so I’m not in a position to give you the extent of the injury.
“What I do know is that it’s his ankle so we will wait and see whether it’s requires an x-ray or a scan.”
Gray also confirmed the fellow defender Lewis Buxton is likely to be sidelined until the end of the next international break later this month.
Buxton has been absent of late with a knee injury and Gray said:
“Lewis is straight line running but Bournemouth on Tuesday will come too soon and I think I can say the same for Rotherham on Saturday.
“My feeling is that he will be back after the international break later in November.”