Karl Lacey appears to be a major doubt for Donegal's Ulster Football semi-final against Down on 23 June after having cartilage removed from a knee in an operation on Thursday.
Lacey has not been ruled out of the game yet but looks to be facing a race against time to be available.
The Four Masters club-man missed the entire National League after undergoing a hip operation in December.
Lacey picked up the injury while playing a Donegal Club Championship match against Ardara last weekend.
A further source of concern to Donegal boss Jim McGuinness will have been Neil Gallagher having to leave the pitch after picking up a knock during Glenswilly's county championship encounter against Bundoran on Saturday evening.
Frank McGlynn could also be a doubt for the Down clash because of a nagging hamstring injury but Mark McHugh is now back to fitness.