Waringstown celebrated winning the Gallagher Women's Senior Challenge Cup for the first time in their history, edging out CSNI in a tense final.
Chasing what looked a modest target of 68, the home side looked on course for a routine win as they reached 45 for 2 in the 12th over.
However, a flurry of wickets including top scorer Rachel Harrison (19) and Mollie Mathers (15) saw CSNI right back in contention.
Teenager Abbie Harrison (15*) was the home side hero as she guided her side to victory, hitting the first ball of the last over to the boundary to spark scenes of great jubilation by the large crowd which had gathered for the showpiece final.
(Batting hero Abbi Harrison)
Abbi Leckey and Nikhita Gondhia picked up two wickets for the Stormont side.
Skipper Leckey had top scored in the CSNI innings, making 18 out of their total of 67 for 6.
Wicket-keeper Rachel Thomas (14) and Beth Healy (10) also made double figure contributions.
Player of the Match Mollie Mathers claimed two for 11, while Waringstown captain Charlotte Lyons also picked up a brace - Cara Murray (1-10) and Jennifer Hanna (1-12) the other successful bowlers.
(Player of the Match Mollie Mathers)
"It was a really close game, with CSNI taking it right to the last over," said winning captain Charlotte Lyons.
"It was a great effort by them after not setting a huge total but they fought all the way.
Lyons praised her team for their efforts in the field, which backed up a disciplined bowling unit.
"I thought we bowled brilliantly, in fact I would say it's the best we have ever bowled, with so few wides, we really bowled very accurately. We were exceptional in the field to only allow them one boundary in their innings."
(Waringstown captain Charlotte Lyons with the Gallagher Trophy)
As with all finals, nerves can play a part even when chasing a low target, but Lyons praised the efforts of teenager Abbi Harrison for getting her side over the line.
"Abbi is a very strong player and she backed herself to win the game and did it for us. It was a great innings and we were all confident she could do it.
"This is the first time we have won the competition having lost four years ago to North Down. I feel this is the start of something for the side, as we have a lot of young players who can only get better."
GALLAGHER WOMEN'S CHALLENGE CUP FINAL
At The Lawn, Waringstown beat CSNI by four wickets
CSNI 67/6 (20 overs; A Leckey 18, R Thomas 14, B Healy 10; M Mathers 2-11, C Lyons 2-12)
Waringstown 68/6 (19.1 overs; R Harrison 19, A Harrison 15*, M Mathers 15; A Leckey 2-10, N Gondhia 2-14)