McGrath had to be withdrawn before half-time in the victory over Kildare in the quarter-final with a hamstring problem, while Hegarty has been troubled by a knee injury of late.
Hegarty came through a full training session on Tuesday night and is almost certain to start, but the situation regarding McGrath is less clear cut.
If he fails to prove his fitness in time for Sunday, his place will likely be taken by Eamon Magee, who did well when introduced for McGrath against the Lilywhites.
In that game, Jim McGuinness had named captain Michael Murphy in his first XV although he was suffering from a hamstring injury.
Murphy started the game on the bench, but was introduced in the first half and wreaked havoc in the Kildare defence but is believed to be in top form for tomorrow’s clash.
Elsewhere, the team remains unchanged, although Leo McLoone is included on the bench after recovering from a facial injury suffered in a club game earlier this summer.
McGuinness is again expected to rely heavily on his bench as he plots Dublin’s downfall through a series of tactical switches.
Donegal’s clash with Dublin throws in at Croke Park on Sunday at 3.30pm.
Donegal: P Durcan; P McGrath, N McGee, F McGlynn; A Thompson, K Lacey, K Cassidy; R Kavanagh, N Gallagher; M McHugh, M Hegarty, R Bradley; P McBrearty, M Murphy, C McFadden. Subs: M Boyle, E McGee, M Boyle, D Molloy, D Walsh, M McElhinney, S Griffin, J Noctor, C Toye, K Rafferty, L McLoone.Tags: