Otago had restricted Canterbury to 221 for nine and was 175 without loss with about 15 overs remaining.
Hamish Rutherford had just posted his sixth one-day century and Rob Nicol was batting nicely on 78.
Wasp — winning and score predictor — was predicting a 99% chance the visiting side would run away with the win at Rangiora.
Cue catastrophe. The Volts lost seven wickets in about 30 minutes to turn a canter into a scrambling win.
Some of the dismissals were the result of chasing the bonus point. But once that had eluded the team, the wickets kept falling.
Seamer Jacob Duffy swung away a six and a four in a hard-hit cameo of 16 to help seal a three-wicket victory.
But the groundwork had been laid by an impressive bowling effort and the huge opening stand between Nicol and Rutherford.
"We lost a couple trying to get the bonus point and then we lost a few more," Volts coach Rob Walter said.
"They were poor dismissals against Todd Astle which made the game a little bit closer than it should have been, to be fair."
Astle took three for 35 and also top-scored for Canterbury with 51. He did his part but Otago dominated the majority of the game.
"That was an area we could have done better but I thought the bowling effort was excellent."
Seamer Jack Hunter got the biggest haul of wickets for Otago with three for 19 from just four overs.
The 22-year-old right-armer removed Chad Bowes for four in the opening over. The Taieri seamer struck again in his next over, finding the edge of Leo Carter’s bat before he had opened his account.
That brought suspended England all-rounder Ben Stokes to the crease.
Stokes signed with Canterbury as its international player despite legal issues stemming from his alleged involvement in an assault outside a Bristol nightclub in September, which left a man with a fractured eye-socket.
His stay at the crease was brief. The Christchurch-born 26-year-old chopped on for just two. Part-time left-arm spinner Anaru Kitchen claimed the glory and Canterbury was left reeling at eight for three.
Michael Pollard and Cole McConchie got the rebuild under way with a partnership of 62.
Nicol eventually broke the union, trapping Pollard lbw for 30 and nicking off McConchie for 40.
Among Nicol (two for 34), Kitchen (one for 34), Michael Rippon (one for 41) and the rarely-sighted spin of Rutherford (none for 13), Otago got through 32 overs of slow bowling.
In the other games, Black Caps wicketkeeper BJ Watling scored 115 to help Northern Districts beat Wellington by five wickets in a last-over thriller in Whangarei.
In New Plymouth, Tarun Nethula set up a five-wicket win for Auckland with four for 64 against Central Districts.
