DESPITE losing Rory Kavanagh to a straight red card on the stroke of half-time, Donegal had far too much desire against a lacklustre Mayo side in Ballyshannon.
Kavanagh was sent off following an incident after he was fouled by Kevin McLoughlin, but Donegal made light of the disadvantage with their best display of the year.
Michael Murphy and Colm McFadden were back in scoring form, with McFadden accurate from frees and Murphy causing plenty of problems at full-forward.
Mayo had the strong breeze in the opening half and looked to be in control when Conor Mortimer put Enda Varley through for a goal on 10 minutes, after Eamonn McGee failed to cut out a centre.
Alan Dillon had Mayo 1-2 to 0-1 ahead on 16 minutes, but Donegal began to find their feet and an inspirational point from Murphy, with three Mayo men on top of him, got Donegal going on 22 minutes. It was obvious that he was causing Mayo full-back Ger Cafferkey plenty of problems at that stage.
Points from Murphy and McFadden (three frees) had Donegal back within a point but Conor Mortimer kept Mayo in front, also from frees, before Kavanagh was shown red by Marty Duffy two minutes into added-time.
The 1-5 to 0-6 Mayo half-time lead was wiped out within seven minutes of the restart, with Karl Lacey and McFadden pointing. Donegal could have been ahead but for a very brave save by David Clarke as Murphy won a high ball and fired for goal from point-blank range.
Young Patrick McBrearty put Donegal ahead for the first time on 44 minutes and they quickly built on that through McFadden and a spectacular score from Leo McLoone.
By the time Mayo lost Cafferkey to a second yellow card on 62 minutes, Donegal were five clear.
There were 33 minutes and 56 seconds on the second-half clock before 'keeper Clarke pointed a '45' for Mayo's first score of the half. McFadden and Murphy added further points before Michael Conroy got a second Mayo consolation score.
"The most pleasing aspect for us was the way we responded to the sending-off. Everybody tried to get up the field with a wee bit more intent and purpose. Leo (McLoone) kicked a good score and set up a few scores," said Donegal manager Jim McGuinness.
Man of the Match: M Murphy (Donegal)
SCORERS -- Donegal: C McFadden 0-7 (6f), M Murphy 0-5 (2f), P McBrearty 0-2, L McLoone, K Lacey, M McHugh 0-1 each. Mayo: C Mortimer 0-3 (3f), E Varley 1-0, D Clarke (1 '45'), K McLoughlin, A Dillon, M Conroy 0-1 each.
DONEGAL -- P Durcan 7; F McGlynn 6, E McGee 6, P McGrath 6; A Thompson 7, K Lacey 7, L McLoone 7; R Kavanagh 5, N Gallagher 7; M McHugh 5, R Bradley 6, M O'Reilly 6; C McFadden 6, M Murphy 8, P McBrearty 7. Subs: M McElhinney 6 for O'Reilly (h-t); D Molloy 5 for Bradley (55); D Walsh 5 for McBrearty (69).
MAYO -- D Clarke 7; K Keane 5, G Cafferkey 4, K Higgins 7; P Gardiner 5, D Vaughan 6, L Keegan 5; S O'Shea 5, B Moran 5; K McLoughlin 6, A Moran 6, A Dillon 6; C Mortimer 5, A Freeman 5, E Varley 6. Subs: P Harte 5 for Freeman (h-t); R Feeney 5 for Keegan (43); C O'Connor 4 for Varley (60); J Doherty 4 for McLoughlin (69), M Conroy 4 for Mortimer (69).
REF -- Marty Duffy (Sligo).