East Coast then equalised in the 56th minute after a succession of quick taps on penalties, as Wharehinga again barged her way over for a double, but it was short-lived as the hosts spilled the restart and from the scrum, Whanganui spread the ball wide to winger Teresa Rennie to dash away to the corner.
An Ireton penalty established a 25-17 buffer, but East Coast came charging back at the death, getting an attacking lineout and moving the ball to winger Dane-a Kopa to just reach out and score.
But Whanganui kept their composure, trapping East Coast in their own half until securing a ruck penalty to kick the ball out for fulltime.
Coach Junior Nepia had made a handful of key positional swaps in the back three and the forward pack, and they all came up trumps.
“Especially at set-piece time, our set piece went really well on our scrumming side, a few overthrows with our lineout but they adjusted those fairly quickly,” Nepia said.
“We knew that if we came here and we played better than what we did last week, we’ll give ourselves an opportunity, and we did that.
“We brought a bottle of Whanganui River water with us – we put that on the field before the game, just for a bit of home with us.
“We needed that, the river’s a part of our identity and where we’re from, we used that as our connection piece.
“All we know is they gave their best today, our team did.”
Whanganui 25 (T. Barrett, T. Kauika, T. Rennie tries; A. Ireton 2 pen, 2 con) bt East Coast 22 (N. Wharehinga 2, T. Haua-Kahaki Rei, D. Kopa tries; K. Goldsmith con). HT: 17-12.