Defending champions Balbriggan made light work of title hopefuls Leinster with a 9-wicket demolition at Rathmines.
Batting first, Leinster went from 26 for 0 to 44 for 7, blown away by three wickets apiece for Matt Pollard and Sam Willemse, with Andy Darroch taking two.
Peter Francis hit 34 but a total of 114 was never going to be enough.
Farooq Nasr hit 13 fours and a six in his unbeaten 67 from 45 balls, sharing a second wicket stand of 95 in 14 overs with Cameron Rowe (30*).
The statement win meaning Balbriggan aren't going to relinquish their crown without a fight.
Clontarf dug deep to inflict a 21-run loss on Merrion at Anglesea Road.
Irish internationals David Delany (51) and PJ Moor (41) shared a fourth wicket stand of 72 as the Castle Avenue side made 218 - vital late runs coming from Ruan Cronje who shepherded the tail on his way to a top score of 56 from 39 balls (7 fours, two 6's).
Merrion look well placed in the chase with John Anderson making a half century, but not for the first time this season, they collapsed under scoreboard pressure to lose by 21 - three wickets for Fionn Hand and two apiece for John McNally and Delany.
Merrion did give a debut to South African Jordan Neill - who has been playing for Ireland Under 19s in Scotland as well as Munster Heat.
Adam Rosslee's unbeaten 110 propelled YMCA to victory over The Hills.
The Irish hopeful struck 9 fours and a 6 in his 117-ball knock, sharing stands of 88 for the fourth wicket with Ash Burton (43), and 93 in just 12 overs for the 6th with James Forbes (46) as YM made 263 for 6.
The Hills briefly threatened with Cormac McLoughlin's half century and a brisk 40 from Nicolaj Laegsgaard, but Harry Tector's four wickets saw them dismissed for 146.
Hunter Kindley's brutal 145 helped Malahide to an 81-run win over Railway Union at Park Avenue.
He thumped 17 fours and cleared the ropes three times in his 108-ball innings, sharing a second wicket stand of 187 in 20 overs with Younas Ahmadzai.
The Afghan has made quite a name for himself in his first season in Dublin, and he was at his belligerent best, clubbing 8 fours and 6 sixes in his 88 from only 52 balls as the villagers made 293 for 6 in 33 overs.
Kelvin Donnelly took three early wickets and only Ireland U19 international Philippe Le Roux's even time unbeaten 89 (7 fours, 2 sixes) held up the win.