Diarmuid Carey took six wickets as the Southern XI beat NCU by 50 runs, while a fine all-round display by Mitchell Thompson saw defending champions Leinster defeat the NW by four wickets in the U17 interpros.
At Belmont, half centuries from Seanan Jones (69) and Stephen Black (59) in a stand of 106 for the 3rd wicket helped the Southern XI to 259.
There were also useful contributions from Diarmuid Carey (43) and Ben Askew (27), while Donaghcloney Mill seamer Luke Allison took 4 for 43.
The NCU opening pair of Oliver Metcalfe (33) and Harry Warke (29) shared an opening stand of 69 to get the NCU chase up and running, but the introduction of Carey wreaked havoc.
Four wickets fell for just seven runs, and he went on to claim 6 for 31 - the second Southern player to claim six wickets after Cillian McDonnell did it against Leinster - as the NCU were dismissed for 209.
James Hunter hit 9 fours in a battling 68, but it was all in vain.
Leinster beat the NW at Moylena in a competitive match after the NW side dug in and posted 197 for 8.
Fox Lodge left-hander Aidan Logue top scored with 50 from 52 balls (6 fours, 1 six), while Kyle Magee, Rhys Logue and Gregory McFaul all got into the twenties.
Mitchell Thompson (3-39) and JJ Garth (2-22) were the most successful of the Leinster attack, and both were in the runs in the Leinster reply.
Thompson top scored with 69, while Garth made 38 in a 3rd wicket stand of 59.
Bready speedster Gregory McFaul took 3 for 39 to give the NW a glimpse of an opening, but 40 from Gavin Hoey and a run-a-ball unbeaten 15 from David O'Halloran saw Leinster prevail.
The series continues today when the NW face the Southern XI and Leinster face the hosts NCU.
At Moylena, Leinster beat NW by 4 wickets
M Poskitt lbw b JJ Garth 19
R Logue c Hoey b Ruttle 26
J McCombe c&b Garth 1
K Magee c Dempsey b Thompson 25
W Finlay c Garth b Thompson 10
A Logue not out 50
A Doherty c Garth b Thompson 0
A Boyd c Garth b Stiles 0
G McFaul b Hoey 20
B Mills not out 15
Extras (2lb, 29w) 31
Total (8 wkts, 50 overs) 197
Did not bat: T Killen
Fall: 1-57 2-60 3-64 4-106 5-107 6-107 7-108 8-155
Bowling:A Neary 4-0-16-0; G Hoey 6-0-36-1; S Ruttle 10-1-26-1;
JJ Garth 10-1-22-2; C Nulty 4-0-26-0; M Thompson 10-1-39-3; A Stiles 6-1-30-1
M Thompson run out (McFaul) 69
S Lynch b McFaul 12
A Stiles b McFaul 3
JJ Garth lbw b Mills 38
SJ De Klerk c Magee b McFaul 4
G Hoey c Mills b Killen 40
D O Halloran not out 15
A Neary not out 2
Extras (1b, 12w, 3nb) 16
Total (6 wkts, 44.2 overs) 199
Did Not Bat: S Ruttle, T Dempsey, S Ruttle
Fall: 1-26 2-38 3-97 4-119 5-166 6-181
Bowling: A Doherty 6-0-32-0; G McFaul 9-1-29-3; T Killen 8-1-32-1; W Finlay 4-0-17-0;
A Boyd 4-0-18-0; B Mills 8-0-31-1; K Magee 3-0-18-0; R Logue 2.2-0-21-0
At Belmont, Southern XI beat NCU by 50 runs
L McDonough c Reid b Allison 4
S Black b Malone 59
H Archer b Allison 0
S Jones st Reid b Glass 69
D Carey b Simmonite 43
B Askew b Allison 27
M Collins c Burton b Simmonite 7
E MacKay c Metcalfe b Allison 10
J MacNulty run out (Reid) 8
JJ Walsh b Hunter 2
C McDonnell not out 3
Extras (6b, 8lb, 6w, 2nb, 5pen) 259
Total (all out, 49.1 overs) 259
Fall: 1-16 2-16 3-122 4-187 5-195 6-215 7-226 8-237 9-243 10-259
Bowling: L Allison 9-0-43-4; J Hunter 9.1-1-31-1; A Simmonite 10-0-52-2;
E Hanna 7-0-39-0; R Malone 6-0-31-1; M Glass 8-0-44-1
H Warke c McDonnell b Carey 29
O Metcalfe c MacKay b Carey 33
R Malone c McDonnell b Carey 7
A Clarke c Archer b McDonnell 0
M Burton run out (Black) 20
J Hunter c McDonnell b Carey 68
A Reid c Askew b Carey 2
M Glass st McDonough b Carey 18
L Allison b Jones 14
A Simmonite b MacNulty 5
E Hanna not out 1
Extras (1b, 4lb, 7w) 12
Total (all out, 48 overs) 209
Fall: 1-69 2-69 3-72 4-76 5-111 6-118 7-183 8-193 9-203 10-209
Bowling: J MacNulty 9-1-37-1; S Jones 9-0-47-1; C MacDonnell 10-0-29-1;
D Carey 10-1-31-6; JJ Walsh 8-0-46-0; E MacKay 2-0-14-0