Greystones came from behind at Lakelands Park to pip Terenure College and move off the bottom of AIB League Division One.
Tries from Leinster scrum-half Cillian Willis (66 minutes) and full-back David McKechnie (75) helped 'Stones to their first win in six league meetings with Terenure.
The hosts, who had lost their last four league games, strode into a 16-6 half-time lead thanks to a try from lock Darren Egan and three penalties from full-back David McAllister.
However, 'Stones upped the tempo to notch a vital win.
It was an evenly-balanced first half during which the sides tried their best to play good rugby in the poor conditions.
Greystones struck first with their out-half James Power, who has been capped at Leinster 'A' level, angling over a penalty in the 15th-minute.
'Nure replied a little over ten minutes later when the Leinster-capped McAllister, who started at full-back owing to former captain Shane Cullen's inclusion at number 10, knocked over a penalty.
Cullen moved the home back-line well through this encounter and after Power and McAllister had traded further kicks – a drop goal and penalty respectively – Terenure began to gain momentum.
A surging break, involving Niall McCann, Kevin O'Dwyer, skipper Stephen Nolan and Bertrand Guiry, showed what the Dubliners are capable of and they broke the try deadlock moments later when a big drive ended with lock Darren Egan getting over.
McAllister tagged on the extras and also notched a third penalty as 'Nure ended the first half on the up. But 'Stones bounced back in the final quarter.
After a great spell of pressure, a 'Nure error saw Guiry slip as he attempted to win a lineout, which allowed the visitors to get back on the front foot. Quick ball allowed Willis to dance his way over and Power converted for a 16-13 scoreline.
Willis had a hand in the clinching try for McKechnie as he made the initial break that led to the experienced full-back's third and undoubtedly most important try of the league campaign to date.
Scorers:
Terenure College: Try: Darren Egan; Con: David McAllister; Pens: David McAllister 3
Greystones: Tries: Cillian Willis, David McKechnie; Con: James Power; Pen: James Power; Drop: James Power
