Donegal will have to face the Dubs again next weekend in the league semi-final after their one point defeat to Monaghan in Castleblayney.
A Colin Walshe point in the fourth minute of added time was enough to secure the win for Monaghan on a 1-10 to 1-9 scoreline.
Because of scorelines elsewhere, the defeat didn't matter and even though they lost their last four league games, amazingly Donegal are through to the Allianz League semi-finals, which are fixed for Croke Park on Sunday next with the Donegal Dublin game at 4 p.m. preceded by Roscommon v Kerry at 2.
Defeat for Cork, and Mayo failing to win by a very large margin, means that Donegal finish fourth by virtue of a much superior score difference. Donegal, Cork, Mayo and Monaghan finished on 6 points and Cork are relegated to Division Two along with Down.
Monaghan needed the narrow victory to avoid relegation and there was huge jubilation among their supporters when the final whistle was sounded.
Donegal will wonder how they let a seven-point lead after 19 minutes (1-4 to 0-0) slip. They had opened really well and a well worked Martin McElhinney goal was no more than their workrate deserved.
But they allowed Monaghan back into the game and there were only three points between the sides at half-time.
Monaghan threw everything they had at Donegal in the second half and thanks to four Conor McManus frees they got back on terms, but they needed corner-back Walshe to come forward to decide the game.
The other scorelines were - Roscommon 1-12, Dublin 1-13; Kerry 0-20, Cork 1-12; Mayo 1-19, Down 1-16.