Big prop Tietie Tuimauga, who nearly set up a try with a big burst, took a back step to no-one, being well supported by tryscoring lock Gavin Thornbury, who lifted his tiring side when he snatched a floating Waikato pass to dash over beside the posts in the 68th minute.
Sixty minutes and they couldn't move our scrum until we had to make some changes.
Lindsay Horrocks stood up to be counted in the battle of the halves - no mean feat when his opponent was 23-capped Irish international Isaac Boss.
Wanganui's biggest weakness was adjusting the new laws, especially staying on their feet as referee Mike Lash watched the breakdown like a hawk.
The step up in the speed of the game created a fine line between diving for a loose ball and not maintaining footing in a two-man ruck.
Starting the second half with 14 men didn't help either as lock Sam Madams was sinbinned for retaliatory punching on Waikato flanker Mitch Jacobson, with Wanganui holding out until right at the end of his sentence when Waikato scored.
The real string in the bow for the visiting forwards was when they drove through the Mooloo pack to put reserve flanker Jamie Hughes over in the corner during the last five minutes, creating a very respectable 27-12 scoreline although there was enough time left for the Shield holders to get one back with their own controlled forward drive from a penalty lineout.
It was only around the 57-67th minutes, where Waikato scored two of their six tries, that the hosts had any real ascendancy - getting big yards with control phases from their rugged captain Whetu Douglas and lock Brian Alainu'uese among others.
While the Waikato backs weren't as fluid as they would have liked on a muddy day, fullback Jordan Trainor still got through a lot of work and glided expertly into gaps near the line to score two tries, although Wanganui were grateful he struggled with the windy conditions to land only one conversion.
The scoreline was much better than the 51-7 loss to Taranaki in the 2012 Shield challenge, and reflects this could be another great Heartland season given Waikato swept aside the likes of Thames Valley (83-13) and King Country (55-0) in the previous weekend's challenges.
Captain Peter Rowe acknowledged as much when complimented by SKY commentator Matthew Cooper in the post-game interview.
"We wanted to come and try to do it justice.
"Today the boy's fronted at times and showed what Heartland's all about."
It was a shame the team could not secure early points to give themselves a boost, Rowe said.
"We just weren't accurate enough, but that's rugby.
"To drive one [try] over is a big up for us."
Even Douglas complimented his amateur opponents.
"We got a chance to get the jersey dirty. Wanganui put up a good fight."
Coach Jason Caskey was also pleased his side had given a performance worthy of the Shield.
"We were very happy with what they fronted with.
"The early try going against us put us under pressure. [But] to hold them to 10-0 before halftime in that wind...."
He also hoped the side could have scored before the break, but trying to push it against strong defence inevitably led to mistakes.
"It's just being able to take your chances, that's how it is against these professional teams, because there's not going to be many," Caskey said.
"We got heavily caned with the penalty count. But happy we scored a couple of late tries.
"Sixty minutes and they couldn't move our scrum until we had to make some changes."
Young fullback Te Rangatira Waitoka was also complimented by the television commentators, but had to overcome a rough start as his clearing kick went sideways in the wind and Waikato winger Ilisesa Ratuva Tavuyara claimed it to dash into the corner after only three minutes.
After a burst through the forwards, Waikato spread to Jacobson who got an overhead pass to centre Sevu Reece, who put midfield partner and former Wanganui player Tevita Taufui over out wide for 10-0 in the 23rd minute.
But Waikato would not cross again until the 49th minute against 14 men, when flanker James Tucker made a good run and first-five Sam Christie danced into the pocket to put Trainor away.
Douglas took charge with some big runs, including smashing over from a 5m scrum, close enough for Trainor to convert.
Wanganui were penalised after first-five Dane Whale grabbed Alainu'uese's jumper following a charge down, and Waikato spread to both touchlines before Trainor slipped Samu Kubunavanua's tackle to score at 27-0.
But if Waikato thought Wanganui would finally lie down they were very mistaken as the towering Thornbury seized on his chance to snatch a long pass and go over beside the posts.
Having held back every reserve except veteran hooker Cole Baldwin, Caskey now rushed his entire bench on for the last 12 minutes to inject some fresh legs.
As Wanganui worked forward off a couple of penalty lineouts, there could be no more stirring sight than a Heartland team driving through a Mitre 10 Cup side for Hughes to score.
Annoyed at the slight, Waikato's forwards attacked from the kickoff and got their own penalty for a lineout drive to put reserve prop Steven Misa over with time up.
Waikato 32 (Jordan Trainor 2, Ilisesa Ratuva Tavuyara, Tevita Taufui, Whetu Douglas, Steven Misa tries; Trainor con) bt Wanganui 12 (Gavin Thornbury, Jamie Hughes tries; Dane Whale con). HT: 10-0.