Cavan 0-15 Down 2-7
Cavan came from six points down to reach the Ulster minor football final for the second time in three years.
That looked an unlikely prospect when Down hit two goals in the opening 20 minutes in the Athletic Grounds, from Ruairi McCrickard and Liam Kerr.
James McCartan's side led 2-2 to 0-2, but Cavan responded.
After surviving a 20-minute scoring drought, they hit four points in a row either side of half-time, with midfielder James Smith outstanding in the air, winning seven clean marks to give Cavan rolls royce possession. He also scored two points from play.
They were growing in belief. Oisin Pierson shone with 0-5, four in the second half, and he pulled them level in the 41st minute.
Cavan goalkeeper Gary O'Rourke narrowed the angle and pulled off a great save from Brendan Gallen to keep the momentum with his team.
They didn't panic once they got their noses in front either, Cian Madden nailing a handy 0-3 from play in the second half and Patrick Lynch also fisting over.
Pierson was influential in the closing stages as Cavan stretched their lead out to four.
Down didn't score for 12 minutes yet hit the last two points, but Cavan deservedly held on to set up a rematch of their 2015 Ulster final defeat by Derry.
Scorers - Cavan: O Pierson 0-5 (1f), P Lynch 0-4 (3fs), C Madden 0-3, J Smith 0-2, S Keogan 0-1; Down: L Kerr 1-1, R McCrickard 1-0, C McCrickard 0-3fs, D McClements, R McCormack, A Gribben 0-1.
Cavan - G O'Rourke; J Cooke, P Meade, K Brady; P Rogers, E Fortune, D Cusack; R Patterson, J Smith; K Hendrick, C Madden, O Kiernan; O Pierson, P Lynch, S Keogan. Subs: K Cosgrove for Patterson (BC, 18), P Nulty for Fortune (44), T Reilly for Cosgrove (54).
Down - J Hazard; C Fitzsimons, B Gallen, T Gordon; F McElroy, P Fegan, S Annett; R McCormack, R McCrickard; R Anderson, C Clarke, D McClements; T Prenter, C McCrickard, L Kerr. Subs: L Middleton for Prenter (41), R McEvoy for R McCrickard (54), A Gribben for Anderson (54), R Carr for McClements (60).
Ref - S Laverty (Antrim)
It was only a second championship victory in three years as Armagh manager but wherever in the ground Kieran McGeeney watched last night's All-Ireland football qualifier win from, he'll be feeling a lot better about life as a county manager.