Sheffield United full-back Jayden Bogle and striker David McGoldrick have both been ruled out for the rest of the season.
Bogle, 21, has undergone knee surgery and is expected to be sidelined for six months.
McGoldrick, 34, has a thigh injury that requires an operation.
The former Republic of Ireland international, who is out of contract in the summer, has scored 27 goals in 127 league appearances for the Blades.
Sheffield United have climbed to sixth in the Championship following an eight-game unbeaten run.