Gethin Kelleher was the Ireland hero with the Railway Union all-rounder showing nerves of steel to score the seven runs required from the last three balls to secure a four-wicket win for Ireland U17s.
The victory sets up a winner-takes-all in the final match of the Celtic Cup on Friday at Stormont. Scotland posted 130 for 7 with Ali Khan making a run-a-ball 47 (6 fours, 1 six), Ollie Pillinger (21), and Shreyas Tekale (20*).
Bonds Glen spinner Sam Haslett took three wickets, while James West picked up two.
The chase was a tense affair, with West enjoying home comforts as the CSNI all-rounder struck 51 from 44 balls (6 fours, 1 six) while there were runs too for Pembroke's Dan Murray (20) and Sam Haslett (18).
A real thriller that went all the way, and Friday's clash could well be the same between two evenly matches teams.
Shlok Thaker had given Scotland a series lead in the morning game as he top-scored with 35 as the visitors chased down a modest Irish total of 100 to win by five wickets with eight balls remaining.
William Shields (2-18) the best of the Irish bowling. Bruce Whaley (35) top-scored for Ireland, while Tekele (3-10), Shlok Thaker (3-17) and Alec McClennan (2-12) did the damage with the ball for Scotland.