Paul Anderson is facing up to six weeks on the sidelines with a fractured forearm and dislocated wrist.
The Nottingham Forest winger, who is on loan at the City Ground from Liverpool, sustained the injuries during Friday's FA Cup clash with Derby.
The 20-year-old fell awkwardly under a challenge from Paul Connolly and required lengthy treatment before being stretchered from the field.
Forest had feared that Anderson would be ruled out for some time and scans have now revealed the full extent of the problem.
The youngster spent Friday night in a Derby hospital but was discharged on Saturday morning.
The news comes as a major blow to Forest boss Billy Davies, with the Reds having found form in recent weeks with a settled side.