Chris Wilder has revealed that defender Richard Stearman will be missing for the foreseeable future having picked up a hamstring injury in the midweek loss at Cardiff City.
Speaking ahead of the weekend's derby clash against Barnsley, Wilder commented: "Richard will be out for two to four weeks, we haven't got the results back yet, but the thoughts of the physiotherapist is that we're looking at a few weeks which is obviously a big blow.
"He's been excellent, he's been everything we expected given his Championship experience and his attitude and experience in the dressing room has been excellent, but other teams will have injuries too and we have to get on with it."
On further changes to the starting XI to face the Tykes, Wilder added: "We'll look at making changes, we have had a tough schedule, the amount of games you play in August is a lot, but everyone goes through the same process.
"We're one of those staff that are looking at the next game as soon as one finishes.
"We're trying to add to the squad quickly, I've talked enough recently about it and we know the squad needs strengthening."