Whanganui had some malfunctions in their lineout which meant they couldn't clear their half after getting penalties, while earlier they got pulled up repeatedly for tackles around the ruck which were creeping into the upper shoulder area – a no-no in the modern game.
Visiting fullback Levi Emery began to open up some holes, while Darling, hooker and skipper Sam Sturgess and No 8 Sean Jansen were always on the charge.
However, after closing to 21-12, North Otago had expended a lot of energy and Whanganui were starting to punish them on defence – as player-of-the-day No 8 Ben Whale and flankers Jamie Hughes and skipper Campbell Hart produced some copy-book tackling around the bootlaces.
Midfielders Ethan Robinson and Kameli Kuruyabaki also lined up some nice hits to force turnovers.
Starting to get more ruck turnovers, and with regular starters like Craig Clare and Semi Vodosese now coming off the bench for impact work, Whanganui cut loose to score three tries in the last seven minutes, when North Otago became desperate to at least force a bonus point.
After a tough game last week against South Canterbury, bloodied halfback Lindsay Horrocks played a key role by swooping on a couple of overthrown lineouts by both teams to set his side on the attack.
Although the result in Te Aroha went against Whanganui, as Thames Valley locked them out of the top two by hammering neighbours King Country, Hart is still confident of going up there on Saturday and winning to confirm a home Lochore Cup game.
"We'll prepare much the same, and try to do it again next week.
"It's finally the composure we've been seeking all year; it's taken us a while to find it.
"It's a big part of that effort to put it on the table."
Revenge was sweet for the Whanganui survivors of the last time the two sides met in the 2019 Meads Cup final.
"We didn't even really talk about that [2019 Meads Cup final] before the game, but that was a game when we didn't really turn up that day at the start," said Hart.
"Today, we really focused on our start and turned up, and it left us in good stead for the rest of the game."
Pleased coach Jason Caskey felt much the same about the big lift mentally since the loss in Timaru.
"We talked about it before the game, about more of a complete performance – part of that was cutting our error rate.
"We've been letting ourselves down badly, making too many errors, and I said 'if we hold the ball for longer periods, we're attacking – we're making the play rather than defending so much like we were last week'.
"First half, opportunities we got, we took them pretty well. They got a lot of field position and we had to work hard to keep them out.
"After that second [North Otago] try, it was getting back to 'game on'. Pretty happy with the way they responded in that last 15."
Once the side adjusted to Henshaw's interpretation of the tackle area, they were able to bring the penalties back a bit and force North Otago to chance their arm with the clock running down.
"Those seatbelt tackles that they're [ruling] now with your arm across, 10 years ago they were fine," said Caskey.
"But now it's just what the changes are, and to be fair, we said at halftime with the forwards about getting that tackle low.
"The Jamies [Hughes] and the Bens [Whale] probably doing it better because they just keep whacking them down low, because [North Otago] kept sending big guys around the corner, but not a lot of play off the back, so you know you've just got to stop the carry.
"When we did that well, we had the opportunity to get over the ball as well, and we were getting rewards with turnovers and penalties."
Getting into position right from the kickoff, Whanganui made a couple of handling errors but stayed focused, and after Horrocks dashed off a lineout to reach the try line, the forwards worked the rucks and the halfback had another chance to dive over in the eighth minute.
After a long time defending their territory, it took some tremendous tackling from the pack and then a 50m clearance by first five Dane Whale to put the hosts down the right end of the field, where they caught their frustrated opposition napping.
Hooker Roman Tutauha worked wide and offloaded to winger Alekesio Vakarorogo to beat three tacklers before being stopped at the line, with Horrocks feeding returning fullback Te Rangatira Waitokia to dive across.
Wanting at least one more score before the break, Whanganui got it when Horrocks landed his chip kick just in front of the 22m, so unable to mark the catch, the North Otago sweeper hurried a clearance that went straight to Robinson.
Whanganui stayed wide and lock Mathew Taula-Fili bulldozed his way through two tacklers to score in the corner, Robinson slotting a good conversion although then just missing a long-range penalty right before the break.
That missed three points was looking crucial after 20 minutes of the second half as Whanganui had to live in their half, North Otago getting a succession of penalties to drive from the lineout, eventually seeing Jansen slip off the back to plant it by the corner flag.
With Emery probing for openings, he earned a penalty for being impeded after a chip kick, and North Otago recycled repeatedly after the lineout win to get close before reserve halfback Owen Davy sneaked over following a quick tap from another infringement.
Defending a nine-point lead with 19 minutes left, Whanganui found another gear as a fresh Clare entered the fray.
The visitors spilled the restart and infringed after the scrum, letting Clare slot a 26m penalty for some more breathing space.
With reserve Timoci Seruwalu making in-roads on the carry, Whanganui got another penalty to get into the attacking 22m where, in a decisive moment, North Otago prop Melikisua Kolinisau just wouldn't stop impeding play and was sin-binned – leaving the side with 14 men for the rest of the game.
Whanganui immediately set an attacking scrum and drove for Taula-Fili, who took it off the back and twisted through two tacklers to score the crucial bonus-point try.
Desperate, North Otago forced a turnover following the restart, but in sweeping wide opened up an intercept for Clare, who got his veteran legs pumping to surprisingly hold off a chasing Emery and run 75m under the posts.
North Otago then tried a reserve side restart which fell straight to Kuruyabaki, who dashed off through the chases to reach the 22m and put winger Josaia Bogileka over in the corner, with Clare slotting the sideline conversion for a 14-point haul in 18 minutes.
Whanganui 45 (Mathew Taula-Fili 2, Lindsay Horrocks, Te Rangatira Waitokia, Craig Clare, Josaia Bogileka tries; Clare pen, 3 con, Ethan Robinson 3 con) bt North Otago 12 (Sean Jansen, Owen Davey tries; Abel Magalogo con). HT: 21-0.
