Armagh produced a superb display to stun Down as the Ulster Football Championship finally came to life.
Down led early on but Jamie Clarke's glorious fifth-minute goal turned the game in the Orchard men's favour.
Armagh moved 1-6 to 0-3 ahead but Mark Poland hit a Down goal and they trailed by only two at the break.
Down moved a point ahead early in the second half but Armagh regained control and they hit the closing four points to earn a deserved win.
In front of 13,107 fans at the Athletic Grounds, the Mournemen hit the opening two scores but Armagh's purple patch of 1-3 without reply was started by Clarke's stunning fifth-minute goal.
The Crossmaglen youngster produced a deft Peter Canavan-like finish with the left foot after a perfect slip-pass from club-mate Tony Kernan, who had won Ciaran McKeever's high ball from midfield.
Kevin Dyas, Clarke and Steven McDonnell added further quickfire points for the Orchard men as Down appeared severely rattled.
Declan Rooney got Down scoring again in the 13th minute but Armagh were still firmly in control - as emphasised by further unanswered scores from the impressive Billy Joe Padden and Aaron Kernan (two).
Down needed a quick response as Poland provided it in the 22nd minute with a glorious goal as he waltzed past three challenges before slotting past the helpless Paul Hearty.
Malachy Mackin and Padden responded with Armagh points by the 25th minute but James McCartan had already made a dugout intervention by introducing Conor Maginn for John Clarke.
Maginn got on the ball on several occasions during the remainder of the first half as Down fought their way rback into the contest.
Clarke's 27th-minute free was followed by two further superb Mourne scores from play before the break with Paul McComiskey and Clarke again on target.
Gerard McCartan's move on Jamie Clarke was proving beneficial as his namesake Daniel had struggled on the Crossmaglen starlet during the opening stages.
Down started the second half in similar fashion as two Marty Clarke frees were followed by another superb McComiskey effort from play.
That put the Mournemen ahead but Aaron Kernan ended a 20-minute scoring drought for the Orchard men by slotting a free which levelled proceedings again.
Down squandered a couple of chances to restore their lead and the misses were punished as Jamie Clarke slotted a superb point after good forward work by Aaron Kernan and McDonnell.
Coulter stormed towards goal in the 51st minute and the Allstar appeared to be fouled by Brendan Donaghy as his shot was easily grasped by Hearty.
It was one of those crucial moments - more so when Aaron Kernan quickly slotted a free at the other end to double Armagh's lead.
At that stage, Coulter - labouring because of a lingering hamstring injury - had to be hauled ashore but a towering Daniel Hughes effort got the Mournemen scoring again.
However, Down were unable to get on terms as Tony Kernan lofted over another Armagh point after Jamie Clarke had shot across the face of goal.
And Armagh's lead was three after McDonnell's diagonal ball to Clarke set up a simple finish for Mackin.
With 11 minutes remaining, James McCartan took off Peter Fitzpatrick and McComiskey with Aidan McArdle and Conor Laverty introduced.
But Armagh were now firmly in control and a Laverty mistake was punished by another Padden point to leave more than a kick of the ball between the teams.
Down hauled off goalscorer Poland with five minutes to go but the Mournemen were looking demoralised as Aaron Kernan lofted over another Armagh score.
In desperation, Down went for goal in the closing minute of normal time as first Donaghy's punch cleared the danger for Armagh and Paul Duffy then deflected a goalbound effort inches wide.
Armagh: P Hearty; A Mallon, B Donaghy, K Dyas; A Kernan, C McKeever, P Duffy; K Toner, C Vernon; T Kernan, BJ Padden, M Mackin; M O'Rourke, S McDonnell, J Clarke.
Down: B McVeigh; D McCartan, D Gordon, G McCartan; B McArdle, K McKernan, D Rooney; P Fitzpatrick, K King; D Hughes, M Clarke, P McComiskey; J Clarke, B Coulter, M Poland.