Despite conceding an early try to the hosts within the first minute, Ulster demonstrated composure, refusing to be rattled. Enniskillen out-half Eddie Keys quickly got the visitors on the board two minutes later, slotting a superb penalty from halfway to settle the nerves, taking the score to 7-3.
Ulster's renowned pack soon made its presence felt. A powerful lineout maul proved unstoppable, driving towards the Leinster line for flanker Henry Keys (Enniskillen) to touch down. Eddie Keys added the conversion, putting Ulster ahead, 7-10.
Although Leinster hit back with a try shortly after from Oisin McKenna in the 11th minute, Ulster maintained their structured approach. Eddie Keys punished Leinster indiscipline with another well-struck penalty in the 16th minute, pushing the Ulstermen one point in front, 12-13.
The Ulster maul was proving a decisive weapon. Another perfectly executed drive from a 5-metre lineout saw Henry Keys barge over for his second try of the afternoon, with his brother Eddie converting flawlessly to establish a 20-12 lead by the end of the first quarter.
Ulster continued to press, and when Leinster captain Eoghan Duffy was sin-binned, Ulster clinically exploited the space. In the 33rd minute, quick hands sent Portadown full-back Mikey Orr clear to score, extending the lead further to 27-12.
After Leinster stemmed the flow momentarily with a penalty from Hugh Duignan, Ulster finished the half with a flourish. Ards centre Robbie Johnston showcased his pace, breaking through the Leinster defence for a superb individual try. Eddie Keys' conversion sent Ulster into the break with a commanding 34-15 advantage.
HT: Leinster Juniors 15 – 34 Ulster Juniors
The second half saw Ulster manage the game effectively. An early penalty from the reliable boot of Eddie Keys pushed the lead out to 22 points.
Leinster chose to assemble a driving maul for hooker Graham Reynolds to claim a try, converted from wide out by Briscoe for 34-19 in the 53rd minute.
Once again, the Ulster lineout provided the platform, and the subsequent maul powered over, with City of Derry winger Davy Graham claiming the try. Eddie Keys' conversion made it 44-22, seemingly putting the result beyond doubt.
A yellow card for Ulster's industrious number eight, Gary Dillon (Dromore), offered Leinster a late opportunity. The hosts capitalised on the numerical advantage, scoring two tries in quick succession through Jake Caldbeck and Isaac Porter to narrow the gap.
However, just as Leinster might have sniffed an improbable comeback, Ulster replacement Angus Christie (Ards) crashed over in the 73rd minute, scoring Ulster's sixth try and decisively sealing the victory.
Leinster managed a final consolation try through their captain Duffy, but it wasn't enough to deny a determined Ulster side who demonstrated their power, clinical finishing, and resilience to secure a vital away win.
Scorers
Ulster
Try: H Keys (2), M Orr, r Johnston, D Graham, A Christie
Conversion: E Keys (5)
Penalty: E Keys (3)
Leinster
Try: E Duffy (2), O McKenna, G Reynolds, J Caldbeck, I Porter
Conversion: M Briscoe (4)
Penalty: H Duignan
Teams
Ulster
15\. Michael Orr (Portadown);14. Jonny Hunter (Dromore), 13. Robbie Johnston (Ards), 12. Dean Dillon (Dromore), 11. Davy Graham (City of Derry); 10. Eddie Keys (Enniskillen), 9. Ryan Flavelle (Cooke); 8. Gary Dillon (Dromore), 7. Curtis Pollock (Ballymoney, Capt),6. Henry Keys (Enniskillen), 5. James Wright (Portadown), 4. Ross Bingham (Dromore), 3. Matthew Millar (Dromore), 2. Angus Cunningham (Lurgan), 1. Orran McIlmurray (Lurgan),
Replacements: Tom-Arthur Donnan (Cooke), Neil Rutledge (Enniskillen), Ryan Emerson (Lurgan), Jack Rutledge (Enniskillen), David Brown (Ballymoney), Michael Rooney (Enniskillen), Angus Christie (Ards), Adam Keating (Dromore).
Leinster
15\. Eoghan Duffy (Boyne, Capt), 14. Walter Walsh (New Ross), 13. Robbie Vallejo (Boyne), 12. Michael Russell (Clondalkin), 11. Oisin McKenna (Seapoint); 10. Micahel Briscoe (Boyne), 9. Hugh Duignan (Suttonians); 8. Dylan Lynch (Boyne), 7. Garry Dunne (Kilkenny), 6. Gavin Kelly (Bective Rangers), 5. Jake Caldbeck (Kilkenny), 4. Isaac Porter (Gorey), 3. Conor Kelly (Bective Rangers), 2. Darren Browne (Midland Warriors), 1. Scott Caldbeck (Tullow),
Replacements: Graham Reynolds (Balbriggan), Dewald Barnard (Wicklow), Josh Evans (Kilkenny), Conor Smyth (Cill Dara), Tiernan Gonnelly (Dundalk), Stephen Hendy (Gorey), Craig Cantwell (Bective Rangers), Cormac Hurley (Seapoint).