Antrim fought back from the jaws of defeat on two occasions to draw 3-14 to 1-20 with Armagh after extra-time in the Ulster U21 quarter-final.
The Saffrons came back from seven points down with two minutes left of normal time to level.
Armagh let slip a six-point lead in extra-time as Antrim's second fightback secured a replay next Wednesday.
The winner of the replay with meet Donegal, who hammered Fermanagh 3-10 to 0-6 in Ballybofey, in the semi-finals.
Goals from Willie Gillespie, Ciaran Brennan and Patrick McBrearty (penalty) helped Donegal to a comfortable win.
Antrim had their noses in front for most of the first-half at the Athletic Grounds and Ronan McGrady's penalty put them 1-2 to 0-2 ahead after 15 minutes.
McGrady converted the penalty on 12 minutes after Ryan Murray was fouled by Shea Freeman, who received a black card.
Armagh initially struggled with the strong wind at their backs but scored three unanswered points before the break.
Paul McGeown scored his third point of the night, followed by a '45' from Ethan Rafferty and a point from captain Miceal McKenna.
Armagh senior player Ethan Rafferty was the outstanding player on the field and he helped the home side pull away in the second-half.
Rafferty thumped home a 42nd minute penalty as Armagh outscored Antrim by 1-8 to 0-3 in a 15-minute period.
They looked to be cruising to victory, especially when Niall Delargy was black carded to leave Antrim, who had already used all their substitutes, down to 14 men.
However, two late goals from full-forward McGrady, his second a stunning effort in the third minute of injury-time, helped the Saffrons tie the game at 1-14 to 3-8 after an hour's play.
Armagh scored six unanswered points in the first period of extra-time, but Antrim responded with six of their own in an incredible second period.
Armagh: N McCoy; M Finnegan, S Kelly, S Freeman; D O'Neill, D O'Hagan, P Crilly; A Findon, E Rafferty (1-2, pen, 'a 45'); P McGeown (0-6, 2f), M McKenna (0-2), C Comiskey (0-2, 2f); A Nugent, C O'Hanlon (0-2), C McNally
Subs: C Boyle for Freeman (BC, 11), E English (0-4) for McNally (28), J McElroy for Finnegan (42), J Hall (0-2) for Nugent (48), E Burns for O'Neill (66)
Antrim: R Hanna; C O'Rawe, N Delargy, C McCann; M McGarry, C Hamill, E Killough; O Gallagher, D Nugent; R Murray (0-6), K Quinn (0-1), D McAleese; P McBride (0-1), R McGrady (3-4, pen, 2f), L McCurdy
Subs: D McCann for C McCann (20), F O'Neill for McGarry (38), R McCann (0-2) for McCurdy (42), R Lynch for Nugent (45), M Lappin for Hamill (48), P Nugent for Quinn (53)
Referee: Cathal O'Hagan (Tyrone)