Donegal will meet Tyrone in next weekend's Ulster under 20 football final following their 1-11 to 0-12 against Down in Saturday's semi-final, played at the Loup GAA Club in south Derry.
Shaun Paul Barrett's side had reached the last four after a penalty shoot-out victory against Monaghan.
Here, Naomh Columba's Aaron Doherty supplied the decisive score - a goal - in the 27th minute of the second-half to help guide his side to victory.
Tyrone beat Antrim in Saturday's other semi-final in Lavey by 0-11 to 0-9.
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Ulster under-20 football semi-final results
Donegal 1-11 Down 0-12
Tyrone 0-11 Antrim 0-9
Ulster minor football league
Donegal 1-5 Sligo 0-8.
