Donegal and Eoghan Ban Gallagher have suffered a huge blow ahead of this weekend's All Ireland Super Eight tie with Kerry at Croke Park.
The Killybegs man is understood to have suffered a serious leg injury in training.
Donegal officials have yet to confirm the extend of the injury but he will be out for a lengthy period of time.
Gallagher has been one of the consistent high performers for Declan Bonner side's in this years championship.
His driving runs were a key part of the wins that lead to back to back Ulster titles.
Paddy McGrath is also a doubt for this weekend.
The Ardara man was a late withdrawal ahead of last weekends game against Meath after suffering a knock in the warm up.