Derby defender Jay McEveley has had an operation on his fractured cheekbone and could be out for around eight weeks.
The full-back went under the knife on Wednesday, less than 24 hours after suffering the injury in the 2-0 Championship defeat at Middlesbrough.
Should the surgery prove successful, McEveley's absence could be reduced and he could play wearing a protective mask.
The 24-year-old joins an injury list at Pride Park that is already into double figures.