Josh Maja is a doubt for the Boxing Day visit of Bradford City to the Stadium of Light.
The striker is suffering from illness and wasn't fit enough to come off the bench against Portsmouth on Saturday after he started feeling worse as the game wore on.
Maja was due to see the doctor at the Academy of Light this morning to be assessed.
Ross said: “Josh will see the doctor this morning, we don’t know yet. He has a couple of days yet [before the game], it could go better or get worse yet, he is in with the doctor.
“He has a sore throat and flu-like symptoms. We will see how he is.”
Maja was struck down with illness in the build-up to the game at Fratton Park but felt fit enough to be on the subs bench, with Adam Matthews also a late withdrawal with a calf injury.
Ross revealed the striker started to feel worse as the game progressed and it wasn't worth bringing him on and risking him getting worse.
Ross said: “Josh had a little bit of an issue in the morning but wasn’t too bad and he thought he would be okay to be on the bench, then felt worse as the afternoon and game went on.
“He was actually going on but when he was going on he said he felt he didn’t feel great.
"As the game went on he felt worse, in that time of the game, the fixtures we have ahead, do you force him to do it or look at the bigger picture and hopefully have him back for Wednesday?"
Elsewhere, Glenn Loovens will sit out serving a one-game ban while he is also injured, Adam Matthews is still a doubt with a calf problem and Tom Flanagan and skipper George Honeyman are also doubts.
There is good news with Charlie Wyke set to return to the Sunderland squad for Boxing Day.
Ross added: "They all probably fall into the doubtful/not ruled out category - Adam, Tom, George, Glenn is suspended but would have been ruled out anyway.
“They will all be in that 50/50 category. Duncan we have to manage still.
“Charlie Wyke will be in the squad, he played 90 minutes in a training game on Friday and played really well. He has been desperate to get involved.
“Getting those 90 minutes was really important for him. All being well, that is him back in and around it now.
“We’ll have to ease him back in to a degree but great to have him back.”