Danny Wilson has revealed Diego De Girolamo could miss the remainder of the season with a knee injury.
The young striker damaged his knee whilst playing for Italy's U18s against Austria last week, after earlier scoring for the Italians.
The Blades boss says the 17-year-old will be sidelined for the immediate future, although the full picture should become clearer later this month.
Speaking ahead of Tuesday's trip to Crewe, Wilson said: "Diego will have scan on the 20th March to confirm what we feel about the problem. He isn't going to play for a while, but we don't know how long he will be out for at the moment and I am not prepared to speculate.
"It isn't fair on the lad without knowing all the facts, but he will certainly be missing for the next few weeks, minimum.
"We are all gutted for him, especially with him being a young lad. He has got everything in front of him, but all that excitement has been taken away from him now.
"He would have relished the opportunity to feature in the run-in. But this injury is how football is and he will have the support of the club throughout his recovery."