
The debrief will be stark and painful for Dublin when they assemble to begin the build-up to next Saturday's replay.
Over in Castlebar, the mood will be altogether different for Mayo as they feed off the high adrenaline levels produced by a remarkable recovery in the final ten minutes.
It left them euphoric as they exited Croke Park with their All-Ireland ambitions still intact, but they too need to undertake serious self-evaluation after coming perilously close to allowing Dublin surge out of sight just past the hour mark.
The green-and-red must have seemed like a rapidly receding speck in Dublin's rear-view mirrors when Jack McCaffrey's point put them seven ahead (2-12 to 0-11) after 61 minutes.
Mayo had scored only four points up to then in a second half where Dublin appeared to have made a match-winning burst when they scored 1-3 between the 58th and 62nd minutes.
That golden period had been launched by a trademark opportunist goal from sub Kevin McManamon, who toe-poked the ball to the net after Robert Hennelly had made a good save.
Mayo looked a badly beaten docket as they faced into the closing stages but just as Kerry had reeled them in, earning a draw in last year's semi-final, the Connacht champions unleashed a powerful effort which yielded 1-4 without reply.
The goal came from a Cillian O'Connor penalty in the 69th minute after Colm Boyle was grounded as he charged in on the Dublin goal.
Chaos and panic spread through the Dublin ranks as Mayo drove forward with ever-increasing menace and by the time Joe McQuillan sounded the final whistle after playing almost six minutes of stoppage time, Jim Gavin was facing problems he would have thought highly likely earlier on.
In addition to squandering what should have been a match-winning lead, Dublin were left facing the reality that unless they can persuade the GAA's disciplinary authorities think otherwise, Diarmuid Connolly will miss the replay after being sent off on a straight red card deep in stoppage time.
He was dismissed after clashing on the ground with Lee Keegan, who was yellow-carded.
Whether Dublin launch an appeal remains to be seen. They could have further anxiety too as they wait to see if any action is taken against Philly McMahon for an incident with Aidan O'Shea in the second half.
To add to Dublin's troubles, they may have to plan without Rory O'Carroll, who was forced off with a facial injury after only three minutes.
Mayo lost a defender early on too when Donal Vaughan sustained a shoulder injury in the 10th minute. By then, they were a goal down after Connolly steered home a fifth-minute penalty when Paul Flynn was fouled as he steamed in on the Mayo goal
That goal remained the difference between the sides throughout the first half, which ended with Dublin leading by 1-7 to 0-7. Six of Mayo's frees had come from pointed frees by O'Connor, with defender Keegan adding the other.
All of Dublin's points had come from open play, with Ciarán Kilkenny scoring three in a very enterprising performance.
Mayo had started with championship debutant, David Drake replacing Barry Moran in attack and Hennelly coming into goal for David Clarke.
Somewhat surprisingly, Moran wasn't introduced until the 66th minute but it was a case of better late than never as he made a real contribution to Mayo's rescue package.
Mayo pared the lead to a point in the 45th minute and would have done a whole lot better if their finishing had been better. They shot five wides, some from relatively easy chances, in the third quarter and also dropped a shot into Stephen Cluxton's hands.
It created the distinct impression Mayo were headed for another of those deeply frustrating days the have endured so often, especially when McManamon pounced for Dublin's second goal.
They added three points in quick succession and, with Hill 16 in full voice, the scene seemed set for Dublin to freewheel into the final.
However, Mayo refused to accept the apparent inevitability of it all and every so gradually worked their way back into contention.
Dublin became increasingly edgy and as the error rate increased, Mayo began to sense that survival was possible.
A blunder by Cluxton, who was blocked down by Andy Moran, almost resulted in a Mayo goal, but John Small made a crucial save on the goal line in the 65th minute.
It was one of a few uncharacteristic errors by Cluxton, whose poor kick-out after Mayo's penalty goal gave Andy Moran the chance to level the scores in the 70th minute.
Cluxton also missed three long-range frees, the last of which was in the final minute when a point would almost certainly have won the game.
Having clawed their way back from the edge, Mayo will feel that the psychological edge is very much with them heading into the replay, although whether that makes any difference remains to be seen.
The late scoring burst disguises the reality that their starting six forwards managed only one point from open play between them. O'Connor's accuracy from frees was absolutely crucial on a day when the tactic of using Aidan O'Shea as a target man close to the Dublin goal had limited success.
He alternated between there and the half-forward line and while he worked extremely hard, he usually found himself in heavy traffic any time he won possession.
He had grounds for complaint with referee, Joe McQuillan, who ignored a few first-half tugs on O'Shea as he was about to begin a run into space.
McQuillan acted on it early in the second half, making the Dublin defence more circumspect in how they dealt with O'Shea.
Nonetheless, the fact that 1-8 of Mayo's total came from frees and a penalty will be of concern to Jim Gavin as it points to a lack of defensive discipline in the Dublin ranks.
He will also be unhappy over losing midfieders, Michael Darragh Macauley and Denis Bastick to black cards while Connolly's red card could have a serious impact on Dublin's prospects next Saturday.
Scorers - Dublin: D Connolly 1-2 (1-0 pen, 1f), K McManamon 1-1, C Kilkenny 0-3, P Andrews, B Brogan 0-2 each, A Brogan, J McCaffrey 0-1 each. Mayo: C O'Connor 1-9 (8f, 1 '45, 1-0 pen), A Moran 0-2, L Keegan, D O'Connor, K Higgins, A Freeman 0-1 each.
Dublin - S Cluxton; J Cooper, R O'Carroll, P McMahon; J McCarthy, C O'Sullivan, J McCaffrey; B Fenton, MD Macauley; P Flynn, C Kilkenny, D Connolly; D Rock, P Andrews, B Brogan.
Subs: M Fitzsimons for O'Carroll (3), K McManamon for Rock (h-t), J Small for Cooper (43), D Bastick for Macauley (BC, 50), A Brogan for Andrews (54), T Brady for Fenton (58), E Lowndes for Bastick (BC, 67).
Mayo - R Hennelly; C Barrett, G Cafferkey, K Higgins; D Vaughan, L Keegan, C Boyle; S O'Shea, T Parsons; D O'Connor, A O'Shea, J Doherty; K McLoughlin, C O'Connor, D Drake. Subs: P Durcan for Vaughan (10), A Moran for Drake (45), A Freeman for Doherty (62), B Moran for S O'Shea (66), M Sweeney for D O'Connor (70).
Ref - J McQuillan (Cavan)