The new era of Leinster cricket got under way with some surprising results, with Balbriggan beating Clontarf and Malahide defeating North County.
Elsewhere, Pembroke were too strong for Leinster, Merrion crushed Terenure, Phoenix overcame Dublin University, and The Hills edged out YMCA in the tightest contest of the day.
An opening stand of 81 between Dean Carlisle and Conor Fletcher (27) set Balbriggan on the way to a total of 228 at Castle Avenue.
Carlisle, a young South African with a Swedish passport, has settled in Dublin and it mightn't be too long before he gains higher recognition after impressing with a top score of 79 from 125 balls (6 fours, 1 six).
Adam Keefe (20) and Ehtesham Ahmed (22*) added vital runs late on, and it was very much game on at the half-way point.
Kevin Prior (2-29) was the pick of the home side attack.
It looked as if Bill Coghlan would ensure the win as he hit 9 fours in his 77 to guide Clontarf to 152 for 2 in the 38th over.
However, the wheels came off the chase despite 43 from skipper Eoghan Delany - four wickets from Farooq Nasr (4-38), three from Ahmed (3-37) and a brace from Kevin Robinson (2-43) earning the 32 run verdict for Balbriggan.
The other two games in Group B were very much one-sided affairs with league champions Merrion thumping Terenure by 242 runs.
Michael Lewis (pictured) was the first centurion of the season as he hit 13 fours and 5 sixes in his 114 from just 76 balls.
John Anderson and Niranjan Shankar both made 46, while Patrick Tice hit 36 as Merrion racked up 336 for 9 - Ken McDonald taking 4 for 52, and two wickets each for Diarmuid Lynch and Donal Vaughan.
At Sydney Parade, five Pembroke bowlers took two wickets apiece as Leinster went from 40 without loss to 88 all out.
Gareth Delany (26) and Hugh MacDonnell (25) started well, but Josh Little struck twice in quick succession, followed by Barry McCarthy taking the big wickets of Monish Patel and George Dockrell.
The Leinster card had a distinctly binary feel to it, with eight players making 0 or 1.
Pembroke had little trouble chasing down the modest target, with skipper Fiachra Tucker making an unbeaten 39, adding 63 in 12 overs with Theo Lawson (31) as they clinched a seven wicket win.
In Group A, Malahide won the North Dublin derby thanks primarily to a solid batting effort spearheaded by overseas Australian professional Damien Mortimer who top scoerd with 52 on debut.
Matt Ford - son of Ireland coach Graham - hit 39, while Irish international Peter Chase made a valuable unbeaten 37 as Malahide posted 235 for 7.
North County threatened briefly, and were always in with a shout as long as Eddie Richardson was still there, but his dismissal for 52 signaled the end.
Kelvin Donnelly took 3 for 42, while there two wickets apiece for Chase, Ford and James Newland.
The game at College Park proved an attritional affair on a low, slow deck. Overseas professional Matt Kuhnemann top scored with 43, while skipper Lorcan Tucker made 30 as the students made 139.
Ben White (3-39) and Poonish Mehta (2-14) were best with the ball.
Phoenix were solid in their reply, helped by opener Nic Pretorius making 46, adding 51 for the second wicket with Irish international Simi Singh (25).
The five-wicket victory was secured by another Irish international making his debut - James Shannon hitting 28 not out.
At Claremont Road, a nervy affair went to the final over before a Daya Singh inspired Hills clinched the two wicket win.
Singh hit an unbeaten 68 as they chased down what looked a modest target of 156.
Rory Anders (3-19) and Bobby Gamble (2-39) had reduced The Hills to 88 for 7, but Singh proved the difference to seal the crucial win.
Earlier Joey Carroll (3-43) had struck early blows, including the wickets of Jack and Harry Tector to leave YM in deep trouble.
Tim Tector though battled bravely to make 53 as YM gave their bowlers something to defend - it was nearly enough, but not quite.
LEINSTER SENIOR LEAGUE CUP
At Claremont Road, YMCA lost to The Hills by 2 wickets
YMCA 156 (40.2 overs; T Tector 53, J Parkinson 29; J Carroll 3-43, Daya Singh 2-28)
The Hills 157/8 (49.3 overs; Daya Singh 68*; R Anders 3-19, B Gamble 2-39)
At Trinity College, Dublin University lost to Phoenix by 5 wickets
Dublin University 139 (47.3 overs; M Kuhnemann 43, L Tucker 30; B White 3-39, Poonish Mehta 2-14)
Phoenix 142-5 (37.3 overs; N Pretorius 46, J Shannon 28*, S Singh 25; C Hoey 3-26)
At The Village, Malahide beat North County by 46 runs
Malahide 235/7 (50 overs; D Mortimer 52, M Ford 39, P Chase 37*, Anish Desai 24; A Sheridan 3-60, C Sheil 2-48)
North County 189 (46.5 overs; E Richardson 52, A Sheridan 27, Y Cook 20; K Donnelly 3-42, P Chase 2-25, M Ford 2-35, J Newland 2-38)
At Castle Avenue, Clontarf lost to Balbriggan by 32 runs
Balbriggan 228/7 (50 overs; D Carlisle 79, C Fletcher 27, Ehtesham Ahmed 22*, A Keefe 20; K Prior 2-29)
Clontarf 196 (48.2 overs; B Coghlan 77, E Delany 43, M Wright 20; Farooq Nasr 4-38, Ehtesham Ahmed 3-27, K Robinson 2-43)
At Sydney Parade, Pembroke beat Leinster by 7 wickets
Leinster 88 (31 overs; G Delany 26, H MacDonnell 25, H Venter 22*; JJ Garth 2-4, J Little 2-12, J Balbirnie 2-13, B McCarthy 2-19, Shaheen Khan 2-23)
Penbroke 91/3 (23.1 overs; F Tucker 39*, T Lawson 31)
At Angelsea Road, Merrion beat Terenure by 242 runs
Merrion 336/9 (50 overs; M Lewis 114, J Anderson 46, Niranjan Shankar 46, P Tice 36; K McDonald 4-52, D Lynch 2-51, D Vaughan 2-65)
Terenure 94 (25.3 overs; J Webster 45; T Stanton 3-5, T Kane 2-12)