Schools' interprovincial: The Leinster players, to their credit, somehow managed not to sink to their knees in unison when the final act at Templeville Road yesterday saw Ulster winger Richard Fegan cross for a try beside their posts.
It gave the visitors' outhalf John Shiells an elementary conversion to secure the victory.
Coming down the home strait, Leinster looked to have the contest wrapped up - and with it the interprovincial series - after Marc Lynch rumbled over the goalline. James Power kicked over the conversion and followed it up with a penalty to stretch their lead to 16-11.
Ulster needed a converted try and it didn't look like coming until Fegan came off his wing in injury-time to beat a flat defence with his second of the day.
His first try came on 27 minutes when he received a return pass from full back Paul Glover to outsprint the cover to the corner.
That made it 8-6 at the interval, with the only other contributions coming from the boots of Shiells and Leinster's Brian Collins.
The lead was extended further in the second half through another Shiells penalty before the game was interrupted for 15 minutes because of an injury to Ulster secondrow David McIlveen.
SCORING SEQUENCE: 12 mins: Collins pen, 3-0; 15 mins: Shiells pen, 3-3; 24 mins: Collins pen, 6-3; 27 mins: Fegan try, 6-8. Half-time: 6-8; 45 mins: Shiells pen, 6-11; 60 mins: Lynch try, Power conv, 13-11; 65 mins: Power pen, 16-11; 70 mins: Fegan try, Shiells conv, 16-18.
LEINSTER: B Collins; S Durkin, L Fitzgerald, J Power, V Artemiev; A Cummiskey, R Vij; C Healy, C Culliton, R Burke-Flynn; S Dunlop, C McInerney; K Sheahan, M Lynch, D O'Reilly. Replacements: R Gannon for B Collins (49 mins), D Moore for R Vij (51 mins), G Coffey for S Durkin (54 mins).
ULSTER: P Glover; K Corrigan, M McCrea, C Bruce, R Fegan; J Shiells, A Bartholemew; M Ferguson, T Frazer, G Megaw; D McIlveen, A Linten; R Hamilton, W Faloon, D Pollack. Replacements: R Marton for T Frazer (39 mins), O McMurray for P Glover, J Denny for G Megaw (both 55 mins), N Magee for D McIlveen (60 mins).
Referee: B Fitzgerald (MAR).