South Canterbury dominated all phases, pressuring the suspect North Otago scrum, controlling the breakdown area and often forcing turnovers from the home side, which as a consequence received little go-forward ball.
Flankers Ross Hay and Matt Clutterbuck and lock Marc Comb received little support from the rest of the North Otago forwards, who too often seemed more concerned with being ball-carriers than ball-winners.
Behind the stuttering pack Nick Webster had a game he'd rather forget, but diminutive first five-eighth Jeremy Te Huia scored a brilliant individual try and often relieved pressure with some powerful timely kicking.
The rushing South Canterbury defence aided by the pedestrian provision of ball from rucks and scrums gave North Otago three-quarters Ekeroma Sefo and Lemi Masoe too few opportunities.
The loss drops North Otago to third place in pool A, and with it still having to play Buller (away) and Wairarapa-Bush (home), relegation to the Lochore Cup is a very real prospect.
West Coast and Buller, with wins over Wairarapa-Bush and Horowhenua-Kapiti respectively on Saturday, are joint leaders with 10 points, followed by North Otago (9) and Wairarapa-Bush (8).
North Otago coach Mike Mullins had much to ponder after the performance.
"South Canterbury was a team that was looking for its first win of the season and there was no better way to get it than over their arch-rivals," he said.
"They were more urgent than us and got some very good go-forward ball, and we just didn't tackle. As far as the turnovers are concerned, it's going to be interesting to look at the video and see the interpretations at the ruck area and see what's legal and what's not."
South Canterbury's forwards outplayed North Otago in almost every aspect, led by fiery lock Tui Tauelangi, who not only dominated the front of the line-out but was devastating on attack. He received full support from flankers Eric Smith and Chris Damsteegt, who controlled the tackle area.
South Canterbury's ample possession was put to positive use by halfback Scott Norton and first five-eighth Richie Preston.
Preston, who had been in the rugby wilderness for four years, marked his return to the first-class game with a commanding display. His variations of play were timely, his kicking was astute and accurate and he set up a superb try for flying winger Malakai Fonua, who crossed twice.
South Canterbury coach Ken Wills was succinct: "It was a great win and we're very happy. It was our ability to hold on to the ball that made the difference today and gave us the ability to go forward."
After an even first quarter, South Canterbury took the early lead when Preston and fullback Tony Fatai combined to give Fonua some space and he dashed 30m to the corner for an unconverted try.
Five minutes later Comb carved open the defence and Te Huia shot through for the try, which Pale Tuilagi converted to give North Otago a 7-5 lead at half-time.
There was really only one side in it after the break. Preston, with a long raking punt, took play to the North Otago 22m in the 55th minute then fired a long overhead pass to Fonua, who crossed for his second try.
A Tuilagi penalty in the 61st minute got North Otago within two points, before Norton kicked two late penalties to give his side an 18-10 win and deny North Otago what could be a vital bonus point.
In pool B, Wanganui beat Poverty Bay to top the table with Mid Canterbury, which beat King Country. Thames Valley had its first win of the season, beating East Coast 20-5 in Ruatoria.
- South Canterbury 18 (Malakai Fonua 2 tries; Scott Norton 2 penalty goals, Luke Reihana conversion), North Otago 10 (Jeremy Te Huia try; Pale Tuilagi conversion, penalty goal). Half-time: North Otago 7-5.
- Terry O'Neill
