DONS defender Mark Reynolds will be sidelined until October.
The Scotland squad man dislocated his shoulder in the 1-1 Europa League qualifying draw with KF Shknedija last week.
He went to see a specialist and requires a pin to be put in his injured shoulder.
Dons boss Derek McInnes said: “Mark will be getting an operation on Friday and will be out for 10 to 12 weeks. It’s disappointing to lose Mark, but it is necessary.
“We hope to have him back with us as soon as possible.”