North County edged out The Hills by three runs to earn Fingal bragging rights in a tense encounter at Inch.
Skipper Eddie Richardson held his nerve in a tense final over to seal the win, after Cormac McLoughlin-Gavin's half century looked set to deliver the win.
Richardson had earlier hit a fluent 43, building on a solid platform by Salman Aziz (33) and John Mooney (32) as they posted 139 for 8.
Tomas Rooney-Murphy claimed a five wicket haul but in the final analysis it wasn't just enough.
Mikey O'Reilly was another five-wicket hero which helped his YMCA side to victory against Clontarf.
O'Reilly - son of former international Peter - showed he is back and firing after his injury with 5 for 24 as Clontarf threw away a fast start by Robert Forrest (36) as they were held to 96.
It was nearly enough as they made YMCA fight all the way as the Claremont side only got over the line with three balls to spare, primarily thanks to another teenager Tim Tector (33) and an unbeaten 28 from Bobby Gamble.
Leinster and Rush went to the final ball, a scrambled bye off the last ball sealing the win for the Rathmines side as they chased what looked a modest 90.
All the batters struggled in tough conditions, with home skipper Hardus Venter's 34 the crucial innings in a close game.
Phoenix came out on top in another close contest as they managed to beat champions Pembroke at Sydney Parade.
Skipper Adam Chester top scored with 42, while opener Jamie Grassi made 33, while Aaron Cawley's late 29 was to prove crucial in their 131 for 9.
Joe Carroll then took four wickets as Phoenix made it two wins from two.
The other three games were one-sided affairs, with Railway winning again, beating Balbriggan by 9 wickets. Staffordshire seamer Oliver Perry took three wickets as the home side managed just 68 for 9.
Ireland U19 international Alex Stiles (32*) and Kenny Carroll (25*) ensured the easiest of wins.
It was equally as emphatic for defending T20 champions Malahide against Terenure.
Seamus Lynch hit 50 as Terenure made 107, but Greg Ford (57*) and Arjun Muntha (39*) sealed the 9-wicket win in just 12.2 overs.
John Anderson was in the runs yet again, hitting 60 as Merrion beat Dublin University by six wickets chasing 104.
At Jack Harper Memorial Park, Railway Union beat Balbriggan by 9 wickets
Balbriggan 68/9 (20 overs; O Perry 3-8, A Stiles 2-11, E Grehan 2-14)
Railway Union 70/1 (16.5 overs; A Stiles 32*, K Carroll 25*)
At Inch, North County beat The Hills by 3 runs
North County 139/8 ( 20 overs; E Richardson 43, Salman Aziz 33, J Mooney 32; T Rooney-Murphy 5-22)
The Hills 136/7 (20 overs; C McLoughlin-Gavin 53, M Donegan 22)
At Sydney Parade, Phoenix beat Leinster by 7 runs
Phoenix 131/9 (20 overs; A Chester 42, J Grassi 33, A Cawley 29*; F Tucker 2-16, S Ruttle 2-26)
Pembroke 124/9 (20 overs; J Balbirnie 28, R Hopkins 20; J Carroll 4-23, J Lawlor 2-27)
At Claremont Road, YMCA beat Clontarf by 5 wickets
Clontarf 96 all out (20 overs; R Forrest 36; M O'Reilly 5-24)
YMCA 97/5 (19.3 overs; T Tector 33, Bobby Gamble 28*; C Kelly 2-13, Shariful Islam 2-19)
At Angelsea Road, Merrion beat Dublin University by 6 wickets
Dublin University 104/7 (20 overs; Sanil Gupta 46, D Tucker 20; Amish Sidhu 2-11, S Stanton 2-13)
Merrion 108/4 (15.3 overs; J Anderson 60*, C Hoey 2-10, R Bisgood 2-23)
At The Village, Malahide beat Terenure by 9 wickets
Terenure 107/6 (20 overs; S Lynch 50, D Vaughan 24; M Ford 2-18)
Malahide 111/1 (12.2 overs; G Ford 57*, Arjun Muntha 39*)
At Observatory Lane, Leinster beat Rush by 3 wickets
Rush 90 all out (18.3 overs; J Barnes 23; Monil Patel 3-16, M Tonge 2-15)
Leinster 91/7 (20 overs; H Venter 34 ret; E Conway 2-13)