Dylan McGeouch will miss the Carabao Cup clash against Sheffield Wednesday on Thursday night, but manager Jack Ross has no concerns over his long-term fitness.
McGeouch is yet to make his competitive debut for the Black Cats after a stellar pre-season campaign, and did not train with the squad on Tuesday morning.
He remains a doubt for the League One clash against Scunthorpe United on Sunday and Ross is happy to wait until he is fully fit before including him again.
"[His injury] hasn’t really worsened in any respect. Every time he thinks he’s ready to go he just seems to have a little setback with it.
"There’s still an outside possibility he could be involved on Sunday. As I think I’ve mentioned before, Dylan had a few muscular injuries at the beginning of his career and kind of got to the bottom of it and is now meticulous in what he does with his body.
"We’re trying to help him with that so that when he does come back he’s absolutely fine. If he's right when he comes back he'll be fine, if he's not quite then there's the risk of it worsening.
"He’s desperate to get back playing. For me, Sunday is obviously the one we want him for. There’s still a possibility."
Ross also had positive news on injured trio Charlie Wyke, Tom Flanagan and Jerome Sinclair.
While none of those are due to return imminently, they are ahead of schedule and the Black Cats boss has also been boosted by the availability of Ethan Robson and Reece James.
James played 45 minutes for the U23's on Monday night after picking up an injury in pre-season.
Ross said: "He’s [Wyke] doing well. He’s ahead of schedule, he’s back out running so touch wood that will accelerate things. Of course that battle goes on with the medical team because their timescale is usually a little longer. Charlie, Tom Flanagan, Jerome, the good thing is they’re desperate to push to get back quicker.
"They’re desperate to get back playing with us. You have to put the reins on a little with them but that’s encouraging for me.
"Ethan [Robson] trained today, so we’ll include him in the squad for Thursday but we’ll have to assess as today was his first day back. Reece James will be more involved as he needs games.
Winger Aiden McGeady remains some way from a comeback.
"Aiden hasn’t really done anything since the end of last season, he’s had a quite significant amount of time out," Ross said.
"He’s probably a couple of weeks away still and then you have to consider match fitness, because he’ll very much be playing catch up. It will be about three months then when you factor in the summer break."