Three Canterbury bowlers - Carl Anderson (3-4), Ryan Burson (3-21) and Hamish Barton (3-34) - shared the majority of the Otago wickets after a disappointing batting effort by the red-and-blacks.
Otago collapsed to 92 all out in the 28th over, 77 runs short of Canterbury's 169.
Only one Canterbury batsman, Darron Reekers, passed 30, although several others chipped in with scores in the 20s.
Reekers scored his 31 off 39 balls.
Despite being in with a grand chance to record its first win in the four-team competition, Otago faltered early on after Barton, a spinner, opened the bowling with Burson.
New Zealand used the tactic of opening with a spinner (Dipak Patel) with great effect at the 1992 World Cup.
Otago's first wicket fell at 19, and from then on it was a busy time in the southerners' dressing-room as they collapsed to 50 for six and 82 for nine.
Only Simon Forde, with 32, offered any resistance to the Canterbury bowlers. He was eventually bowled around his legs by Anderson.
In the other match, Wellington lost its last four wickets for six runs after initially making a bold effort to match Auckland's 254 for five.
Grant Donaldson (75) and L Kelly (61) had piled on 149 runs in a fourth-wicket stand that had left Wellington needing 80 from the last 15 overs.
Two run-outs were part of the collapse and five overs were left when Wellington was dismissed for 234.
The bulk of Auckland's runs had come in a second-wicket partnership with opening batsman Tim McIntosh (79 run out) and Ian Billcliff (75) adding 154 in 148min.
In today's action, Canterbury meets Auckland, the other unbeaten team, and Otago plays Wellington.
Short scoreboards:
Canterbury Second XI 169 (Robbie Frew 21, Marcel McKenzie 26, Darron Reekers 31, Ryan Burson 24; David Sewell 2-27, Simon Forde 2-26, Neil Rushton 2-25, Graham Greene 2-25, Nathan McCullum 2-27) beat Otago Second XI 92 (Simon Forde 32; Carl Anderson 3-4, Burson 3-21, Hamish Barton 3-34) by 77 runs.
Auckland Second XI 254-5 (Tim McIntosh 79, Ian Billcliff 75, Richard King 35, J Pawley 24no) beat Wellington Second XI 234 (Grant Donaldson 75, L Kelly 61, David Little 39no; Sanjey Silva 4-44, King 2-48).