Allianz Football League Roinn 1
Donegal 0-9 1-17 Mayo
Allianz FL D1: Mayo reach decider
Allianz Football League Division One
Mayo 1-17 Donegal 0-9
By Chris McNulty in Ballybofey
Ryan O'Donoghue's goal, two minutes into the second half, put Mayo into the Division 1 final and all but tagged Donegal's toes for the top-flight's morgue.
Already boasting a five-point buffer when they emerged for the second half, Mayo took the remaining wind from the Donegal sails with their first foray of the new stanza.
A punched Jordan Flynn attempt came off the Donegal bar and, when Mayo managed to win the ball back, O'Donoghue landed the fatal blow. Donegal didn't lay so much as a glove on the Belmullet forward, who tucked low to the Town End net.
Oisin Gallen, on as a half-time substitute, notched up Donegal's first score of the second half in the 55th minute, but O'Donoghue slammed over an instant response.
Aidan O'Shea's 57th minute free put 10 points between them and the end margin would've been greater only for Patton to block a late shot by Mayo sub Tommy Conroy.
Stephen Rochford spent the previous four years traipsing up the N17 when coaching the Declan Bonner-managed Donegal. Rochford, who took Mayo to All-Ireland finals in 2016 and 2017, was coaxed back to his native county as part of Kevin McStay's ticket in August.
Mayo kicked five of the last six points of the first half to take a 0-11 to 0-6 lead into the interval.
Matthew Ruane continued his exhibition with a superb effort in the 31st minute, drilling over from distance. Ruane had landed two fine points earlier in the afternoon and Mayo were firmly in the mood by the time Aidan O'Shea landed his third of the day to open up a five-point lead
A Michael Langan free momentarily stemmed the flow, but Ryan O'Donoghue had the last say of the opening period.
Donegal, who saw 'keeper Shaun Patton save smartly from Fionn McDonagh in the eighth minute, stayed in touch until the closing 10 minutes of the first period.
Ciaran Thompson, having spurned one a few moments earlier, popped over two frees inside of a minute to draw Donegal level at 0-4 apiece on 18 minutes.
That came after Ryan O'Donoghue, picked out in acres of space by Ruane, shot off an upright with Donegal scrambling back.
Donegal twice led in the early exchanges, Eoghan Ban Gallagher and Thompson posting, but Mayo registered three times in the space of as many minutes.
Goalkeeper Colm Reape sailed over a '45 before Jack Carney swept over from the left-hand side and O'Shea swivelled past Brendan McCole to put the Connacht side two in front, 0-4 to 0-2.
Either side of half-time, Mayo took a real grip and Donegal's four-year tenure in Division One is on the verge of ending.
Now, only something resembling a mathematical miracle will save them.
Scorers for Mayo: Ryan O'Donoghue 1-3 (1f), Aidan O'Shea 0-4 (2fs), Matthew Ruane 0-3, Paddy Durcan, Jordan Flynn 0-2 each, Colm Reape ('45), Jack Carney, Paul Towey 0-1 each.
Scorers for Donegal: Ciaran Thompson (2f), Michael Langan (2f) 0-3 each, Eoghan Ban Gallaghan, J Brennan, O Gallen 0-1 each.
Mayo: Colm Reape; Jack Coyne, David McBrien, Sam Callinan; Stephen Coen, Conor Loftus, Paddy Durcan; Matthew Ruane, Diarmuid O'Connor; Fionn McDonagh, Jack Carney, Jordan Flynn; Aidan O'Shea, James Carr, Ryan O'Donoghue.
Subs: Tommy Conroy for Carr (46), Kevin McLaughlin for McDonagh (52), Padraig O'Hora for Coyne (62), Bob Tuohy for O'Connor, Paul Towey for O'Donoghue (both 69).
Donegal: Shaun Patton; Mark Curran, Caolan Ward, Caolan McColgan; Ciaran Thompson, Brendan McCole, Eoghan Ban Gallagher; Caolan McGonagle, Jason McGee; Michael Langan, Daire O Baoill, Conor O'Donnell; Hugh McFadden, Jamie Brennan, Peadar Mogan.
Subs: Oisin Gallen for McColgan (half-time), Jeaic Mac Ceallabhui for Mogan (43), Rory O'Donnell for Thompson (52), Joel Bradley-Walsh for Brennan (60), Kane Barrett for Gallen (62).
Referee: Sean Hurson (Tyrone).