When it come to the Mitre 10 Heartland Championship, they are the true old enemy.
A lot of column inches has been given over to Steelform Wanganui's recent seasons rivalry with South Canterbury, or how Mid Canterbury were the bogey team for round robin matches up until 2018.
But when taking into account the full 14 seasons of Heartland, no team has given the Butcher's Boys more competition than North Otago.
So, it is perhaps fitting that Saturday's ominous fixture in Oamaru will prove decisive for Wanganui's hopes to making the Meads Cup playoffs.
"It's got to be a win for us, that's all there is to it," said coach Jason Caskey.
"It should be a challenge.
"There's a good feeling there [for us], a bit of excitment, it's a good opportunity."
Having not played each other since 2017 at Cooks Gardens – a 10-6 win to the home side – the rivalry had simmered a little in recent years, with Wanganui having won the last four matchups since 2014.
However, this year the pressure is back on, with Wanganui still in desperation mode to make the Meads Cup group after their horror start to the campaign with three losses.
The successive bonus-point wins over West Coast and East Coast at Cooks Gardens have put Wanganui back in the playoffs conversation, as they sit in seventh spot, but only five points behind the three teams currently occupying the top of the table, including North Otago.
Having missed the Meads semifinals since 2013, this season the southerners won all four games in the first half of the round-robin, a number of them clutch victories decided inside the dying minutes, before finally having their flag lowered 18-17 by West Coast in Greymouth last weekend.
At Dunedin's Forsyth Barr Stadium and fortress Oamaru, North Otago picked up home wins over Wairarapa Bush-Bush 25-11 and Thames Valley 22-21, both teams who beat Wanganui.
This followed a great start to the season when they lifted the Hanan Shield off South Canterbury 26-20 in Timaru, while coming from behind to squeeze past Poverty Bay 34-30 in Gisborne.
While Caskey would like to take his strongest possible lineup, a handful of injuries have forced alterations from the winning combinations, while Wanganui will also roll the dice with yet another fresh midfield combination.
Back from a family trip to Fiji, veteran Penijamini Nabainivalu returns at second-five, combining with young Auckland import Amos Pogia, who debuted off the bench for the second half last week against East Coast.
While Tuesday night training was the first time the pair would have met and worked together, Caskey was confident they will find the chemistry to match their skills.
"Peni's a wiley old fox and very cunning.
"Amos is young and can work off him.
"As Peni's getting older, centre is probably more of an ask than No 12."
Last week's midfielders, Ethan Robinson and Troy Brown, move to the bench.
After a strong 80 minute effort last Saturday, lock Peter-Travis Hay-Horton has a family commitment of his own this weekend, with Josh Lane staying in the starting XV to partner Sam Madams.
The big blow is among the props, as right when Wiremu Cottrell has recovered from his sore AC joint, the team loses impact prop Raymond Salu, who hurt his shoulder in diving over for a disallowed try last weekend.
"It was pretty sore this week," said Caskey of the injury.
Despite the disallowed try, Salu had dotted down four times in the last three games, having the x-factor pace and evasiveness to catch defenders unawares.
The front row is completely rejigged with Kamipeli Latu swapping to the bench for Gabriel Hakaraia, while hooker Roman Tutauha resumes his place in front of Dylan Gallien.
Another tryscorer, reserve flanker Samu Kubunavanua, popped his shoulder in the 72nd minute against East Coast and has not trained this week, with Angus Middleton returning to the squad on the bench, as does Ranato Tikoisolomone after last playing in the West Coast game.
As goal kicking could prove vital in the second half, Nick Harding keeps the other backs reserve spot, with halfback Cameron Davies stepping away this week.
Facing them will be a team with plenty of mind and muscle in the forward pack, including three 2019 New Zealand Heartland XV squad members in game centenarian prop Ralph Darling, fellow prop Meli Kolinisau and lock Josh Clark.
"They've got some experience there, that's for sure," said Caskey.
"Like any game, you've got to win that battle or at least be on par."
When 30-year-old halfback Robbie Smith did not have his usual good kicking game in Greymouth, it made all the difference, as Smith has been a match-winner this season with 59 points from 13 penalties and 10 conversions.
Similar to Wanganui's young import brigade of Pogia, No 8 Ezra Meleisea and fullback Shai Wiperi, the southerners have Otago first-five Michael Williams, lock William Kirkwood and loose forward Jacob Coghl – likewise in their early 20's.
Wanganui vs North Otago Heartland games have encompassed two Meads Cup finals and one Lochore Cup final, while from 12 matches overall, Wanganui holds a slender 7-5 advantage, with an even narrower points per game average – 22 to 21.75.
Since 2002, Wanganui have won only three of nine games at Oamaru's Whitestone Contracting Stadium, although this includes their last two visits in 2014-15.
The team flies direct from Whanganui to Timaru tomorrow morning for the hour drive south to Oamaru, where they plan a captain's run at 3.30pm.
Kickoff on Saturday is 2.30pm.
The Wanganui team is:
1. Gabriel Hakaraia; 2. Roman Tutauha; 3. Wiremu Cottrell; 4. Sam Madams; 5. Josh Lane; 6. Campbell Hart (c); 7. Jamie Hughes; 8. Ezra Meleisea; 9. Lindsay Horrocks; 10. Dane Whale; 11. Tyler Rogers-Holden; 12. Penijamini Nabainivalu; 13. Amos Pogia; 14. Vereniki Tikoisolomone; 15. Shai Wiperi.
Reserves – Forwards: 16. Dylan Gallien; 17. Kamipeli Latu; 18. Angus Middleton; 19. Ranato Tikoisolomone. Backs: 20. Ethan Robinson; 21. Troy Brown; 22. Nick Harding.