Darren Hughes' goal at the start of the second half helped 14-man Monaghan to a superb 1-11 to 0-12 victory over Mayo in chilly Castlebar.
On a cold opening night to the 2017 national football league, with snow-capped mountains as a backdrop, red-hot Conor McManus (0-6) was once more the Monaghan talisman as manager Malachy O'Rourke maintained his impressive record of winning in the first round.
The spirited Farney County started purposefully but the hosts eventually hit their stride and a run of five unanswered points from Evan Regan (2), Cillian O'Connor (free), Kevin McLoughlin and Alan Freeman helped them assume a 0-6 to 0-5 interval advantage.
The visitors had led by four points to one after twelve minutes thanks to four successive McManus strikes from placed balls - three frees and a '45'.
Fergal Boland struck a delightful opening point for the home team on two minutes but McManus (free) had the border county level three minutes later and the classy Clontibret clubman's second pointed free edged the away team ahead for the first time on seven minutes. A third successive McManus free made it 0-3 to 0-1 and he then nailed a '45' to leave three between them.
Hughes made it a four-point game on 20 minutes but Regan, O'Connor, McLoughlin, Freeman and Regan again - with a free from distance - all found the range as Stephen Rochford's men finished the opening period strongly.
Man of the Match Hughes' goal on 37 minutes (when he calmly slotted the ball under David Clarke after a typically-cunning McManus assist), followed instantly by a point from inspirational captain Colin Walshe, gave Monaghan an ideal start to the second half. O'Connor pulled back a couple of simple frees either side of a Thomas Kerr effort - 1-7 to 0-8 - but goalkeeper Rory Beggan thumped over a superb 60-metre free to restore the winners' three-point cushion.
A McManus point from play left four between the teams with 15 minutes left but another brace of O'Connor points had the gap back to two with ten minutes remaining and the visitors were reduced to 14 men, Karl O'Connell dismissed for a second yellow-card offence.
Gavin Doogan hit a vital score for Monaghan to leave the goal between them and O'Connor's third brace set up a nail-biting finale only for McManus' exceptional strike from a nigh-on-impossible angle deep into injury time to seal a famous Monaghan victory.
Monaghan - R Beggan (0-1f); F Kelly, D Wylie, R Wylie; C Walshe (0-1), N McAdam, K Duffy; D Hughes (1-1), K Hughes; K O'Connell, S Carey, G Doogan (0-1); C McCarthy, T Kerr (0-1), C McManus (0-6, 3f, 1'45). Subs: D Malone for C McCarthy, R McAnespie for S Carey, O Duffy for T Kerr, J Mealiff for N McAdam.
Mayo - D Clarke; D Newcombe, K Higgins, P Durcan; C Boyle, S Coen, D Drake; D Vaughan, D Kirby; F Boland (0-1), K McLoughlin (0-1), J Doherty; E Regan (0-2, 1f), A Freeman (0-1), C O'Connor (0-7, 5f). Subs: D O'Connor for E Regan, T Parsons for D Kirby, A Moran for A Freeman, C O'Shea for J Doherty.
Referee - C Lane.