Down 14-0 in eight minutes, Whanganui just had to remember these were the kind of firm conditions they have craved all season with their powerful outside backs, playmakers with long passes, and a mobile forward pack, and soon they were putting plays together to run up five consecutive seven-pointers before halftime.
Prop Ranato Tikoisolomone was quick around the ground like an extra loose forward, fullback Ethan Robinson came into the line to open up the passing channels, while second-five Timoci Seruwalu was back on one of his former home grounds and pushing aside tacklers.
Up 35-14 at halftime and with the bonus point locked in, again Whanganui looked to utilise their bench for added minutes - it is easy to forget so many of them are still Heartland rookies in 2022.
It allowed the home side to pull Whanganui into more of a scrap, as a 6-1 penalty count in the visitors favour flipped to 10-8 for the home side by fulltime, while reserve prop Tai Pulemagafa punched his ticket to join the 2022 "Card Club".
That meant reserve flanker Regan Collier had to leave with him to give Whanganui a legal scrum, and the home side took advantage to score two more tries during their absence to close the gap to 42-28 with seven minutes left.
Returned to their full XV, Whanganui again took control in the final stages - flanker Samu Kubunanvanua scoring a deserved try for an 80-minute effort as he, along with No 8 Semi Vodosese, centre Josaia Bogileka, and player-of-the-day, lock Josh Lane, did a lot of offensive and defensive work.
Prop Bradley Fountain impressed in two shifts, coming back on with the yellow card, as did reserve prop Keightley Watson.
Captain Dane Whale was pleased with the recovery after an opening that could have shocked his side.
"We probably talked about them loving the set piece - loving it being slow - and they came out of the blocks absolutely hissing," Whale said.
"So, we didn't plan for them to come out that fast, hot and heavy. Kudos to them, they really did bring it in that first 10 minutes.
"We had to match that, so proud of the boys to be able to turn that pressure around and get the lead back at halftime."
Having dealt with muddy conditions everywhere else they have played and not having that extra traction, Whale said his side just had to stop allowing for factors which weren't there.
"I don't think we were used to the speed of how that was played today, we have been used to being stuck in the mud a bit, so good to get a good win."
Coach Jason Hamlin was also pleased the side had avoided a banana skin-type performance.
"Even though we're training really well, I thought we were still 'on the bus' a bit, mentally," Hamlin said.
"But they were looking good, in terms of being accurate around stuff.
"Two mistakes gave [Horowhena-Kapiti] 14 points, and then they were able to settle themselves down, get a bit of flow on - the type of rugby we want to play, even in these conditions, and it looked good.
"In all reality, we should have been close to 40 points up at halftime, but we were too impatient.
"But they're able to react, and when something isn't going right, able to stem that tide, and put our plans into place.
"There's lots of it that looks good, but there's lots of it that [needs work].
"Guess it's a bit of a coach's dream, in terms of we got the result, got everything we wanted, but there's still stuff for me to show them on Tuesday - to review properly, and we can put some work into them.
"Our ceiling is really high, but unfortunately so is our cellar depth. We just got to get it right, and more often than not, we do that."
Reaching the business end of the season with powerhouses like Thames Valley and South Canterbury looming, Hamlin obviously wants his bench players to be able to deliver in those clutch final 10-15 minutes, and while they were awesome against Buller, the penalty count and pressure they were under in the final quarter here was a little concerning.
"We knew the HK scrum was going to be really strong," Hamlin said.
"The boys fought and fought, a man down in the scrum, and eventually they got over, but we made them work for it - that's what we're really pleased about.
"They're holding their heads high and they're doing the job - execution hasn't been as nice this week as I'd like, but they're out there working, and they're learning what it is to play at this level of rugby and the intensity that it requires.
"Regan Collier's throwing himself around, and he's saving a tackle that forces a forward pass, which buys us the next possession to score the try.
"They're doing it in real time, with real pressure on them, so they're looking good."
The coach was again pleased with Robinson, who slotted a perfect seven from seven conversions.
"When he got himself into the game he looked really good, his kicking game's on song, he took a couple of real difficult catches, but he worked hard to get under the ball, and [was] smart enough to play down the other end when it was required."
Early on, things weren't looking so rosy as, following a back-and-forth kicking duel, Whanganui couldn't hang onto a Horowhenua-Kapiti cross-kick and first five Kody Edwards swiped it up to dash off to the corner, with unerring halfback Jack Tatu-Robertson slotting the extras.
The home side liked that so much they did it twice - another shallow chip just outside Whanganui's 30 metre line, then the spill and centre Kyle Brown dashing away, and although Robinson made a try-saving tackle, the home side recycled to both sides of the park for second five Tautau Kapea to dive through for 14-0.
Getting it together, Whanganui responded as Seruwalu busted three tackles, then Whale combined with Lane to bring them forward for the backline to strike - Bogileka and Robinson putting winger Alekesio Vakarorogo free outside before offloading back to Bogileka for 14-7 after 11 minutes.
With Whanganui's cover defenders forcing Horowhenua-Kapiti to give away penalties at ruck time, the momentum turned and, following a quick tap near the tryline after an unsuccessful 5m scrum, Vodosese was able to do what he originally intended and power through the last line to lock up the scores.
Horowhenua-Kapiti were now feeling the pressure as they tried to spread the ball but offered Whanganui winger Alekesio Vakarorogo a clean intercept to run 50m and score.
Not long after, Vakarorogo took a clean take on another home side clearance, Whanganui going wide, with Tikoisolomone getting over there quickly for the cleanout, which allowed Bogileka to attack down a very short blindside and pop the pass for fellow winger Tyler Rogers-Holden to dash away to the corner.
Whanganui had a couple of chances to add to their lead before halftime, with dropped balls thwarting them, while Tyler Rogers-Holden was denied a double by home fullback Thomas Barnsley's tackle, which badly injured his leg - Whanganui reserve Ben Whale showing his class by coming out to help carry Barnsley to his reserve bench.
The visitors stayed on the attack and when Vakarorogo broke through the midfield, this time the pass was clean for halfback Lindsay Horrocks to dive over beside the posts on halftime.
Whanganui kept it up after the break, as Horrocks fed Robinson running on the attacking angle and he put Bogileka over in the corner, then slotted the difficult conversion.
But being reduced to 14 forced Whanganui to defend for a long time, and finally the home side got through as reserve No 8 Kolinio Koto scored at the back of a 5m scrum drive against seven, Edwards taking the conversion.
Whanganui still seemed safe with 12 minutes left, but Horowhenua-Kapiti muddied those waters when reserve winger Darren Falaniko made an intercept and the home side spread for veteran winger Willie Paia'aua to show a clean pair of heels and score in the corner, then slot the extras due to Edwards limping.
However, with only seven minutes left and returned to a full XV, Whanganui trapped the home side inside their 22m, and although Vodosese was denied an signature attack from a 5m scrum, Watson took a strong carry towards the line, and from the ruck, Kubunavanua took the next pass to score beside the posts.
Whanganui 49 (J Bogileka 2, S Vodosese, A Vakarorogo, T Rogers-Holden, L Horrocks, S Kubunavanua tries ; E Robinson 7 con) bt Horowhenua-Kapiti 28 (K Edwards, T Kapea, K Koto, W Paia'aua tries; J Tatu-Robinson 2 con, Edwards con, Paia'aua con). HT: 35-14.
