James West scored a valuable 42 as the NCU beat Leinster in the first of their four scheduled U13 interpro matches at Ringcommons.
James, son of former international Regan West, had support from Seb Yeates (16) as the NCU posted 100 for 9 in their 20 overs.
Sebastian Dijkstra (5-11) bowled superbly for the young Dubliners.
The reply went right to the last ball, but despite the best efforts of Olly Reilly (49) Leinster fell just three runs adrift.
Seb Yeates and Michael Hollway claimed two wickets apiece.
The teams are due to meet again today (WED) but the forecast is poor for the Belfast area.
(NCU Under 13 squad)
U13 Interprovincial Challenge
At Ringcommons, NCU beat LCU by 3 runs
NCU 100-9 (20 overs; James West 42, Seb Yeates 16, Sebastian Dijkstra 5-11)