Down staged a magnificent second half fight-back to snatch a 1-11 to 0-14 draw with Monaghan at Pairc Esler.
The home side trailed 0-10 to 0-04 at half-time and Jack McCarron stretched Monaghan’s lead to seven points on the resumption.
But Conor Maginn's 40th-minute goal ignited a Down comeback and they closed the gap through Conor Garvey and the impressive Ryan Johnston.
Crucially, Donal O’Hare converted an injury-time free to claim an unexpected opening league point for the Mourne men.
Monaghan were completely dominant in midfield early on and cut through the Down defence with wave after wave of attacks in a desperate first half for the home side.
Down did score the opening point in the fourth minute but soon began to rue the absence of big midfielder Kalum King who was a late withdrawal from the team.
Monaghan took over and scored six points without reply in the next 12 minutes.
Jack McCarron and newcomer Thomas Kerr settled quickly and scored five of those points, three from free-kicks after some ill-disciplined defending from Down.
Paul Finlay scored the other point with a superb long distance point on the run on a fine afternoon for the Ballybay man.
Finlay made a number of spectacular catches from kick-outs and gave Monaghan a lot of possession to build upon, while the Down forwards were starved of the ball for long periods.
Jerome Johnston made the most of a rare opportunity to get the ball in hand and stopped the rot with a much-needed point for the Mourne men in the 18th minute.
Down had to make a change in midfield and Gary McArdle was called ashore early with full-back Peter Turley then switched to the middle.
Monaghan goalkeeper Rory Beggan converted a monster free from at least 50 metres to stretch their lead to 0-07 to 0-02.
O'Hare and Mark Poland tried hard to take the fight to Monaghan, but the Ulster champions were on top in almost every position.
McCarron picked off another lovely point and although rookie Darragh O'Hanlon's free was brief respite for Down, Monaghan scored the next two points to lead by 0-10 to 0-04 at the break.
Down needed something to happen and Maginn's superb soccer-style finish to the net, after a pass from Poland, was the catalyst they needed.
After the 40th minute goal they outscored Monaghan by six points to two over the remainder of the game.
Suddenly, Down were the team with all the momentum and the belief, and substitute Ryan Johnston proved to be a superb ball-carrier and punched holes in the Monaghan defence.
Meath referee, Cormac Reilly angered the Monaghan supporters with a number of decisions in the last quarter.
With Eoin McCartan on target from play, O'Hare reeled Monaghan in with three frees in the last quarter, including the late leveller from 35 metres out.
Down: S Harrison; D McCartan, P Turley, D O'Hagan; R Boyle (0-01), A Carr, C Garvey (0-01); G McArdle, R Mallon; D O'Hanlon (0-01, 0-01f), M Poland, J Johnston (0-02); D O'Hare (0-04, 0-04f), N Madine, C Maginn (1-00).
Substitutes: R Johnston (0-01) for McArdle (21 mins), E McCartan (0-01) for Madine (55), D Savage for J Johnston (67).
Monaghan: R Beggan (0-01, 0-01f); F Kelly, D Wylie, R Wylie; C Walshe, D Mone, C Boyle; G Doogan, P Finlay (0-01); P Keenan, S Gollogly, T Kerr (0-02, 0-01f); J McCarron (0-07, 0-02f) C McGuinness (0-01), D Malone.
Substitutes: C McManus (0-02, 0-01f) for McGuinness (42 mins), K Duffy for Mone (49), V Corey for D Wylie (54), K Hughes for Gollogly (58), O Lennon for Kerr (68).
Referee: C Reilly (Meath)