Netball: Diamonds coach Lisa Alexander reveals struggle coaching against Silver Ferns shooter Maria Folau

Lisa Alexander admits she's been plotting Silver Ferns shooter Maria Folau's downfall her entire coaching career.

And as made clear again during the Silver Ferns' 54-53 win over the Diamonds on Sunday, the Australian coach still hasn't figured out how.

Folau was at the helm of the Ferns' success in the third test of the Constellation Cup in Sydney, slotting 27 goals from 31 attempts at 87 per cent.

Speaking to media after the clash, Alexander acknowledged Folau's success in the goal shooter bib, revealing she was still trying to find a way to shut-down the 32-year-old veteran.

Australia coach Lisa Alexander speaks to players during the match. Photo / Getty

"I've had to coach against her for the past eight years and try and plot her downfall," Alexander said. "She's actually really hard to plot the downfall on now because she plays a role and is really disciplined with it.

"I think Maria has done extremely well to play the role now that she's playing in shooter, I'm actually admiring that."

Maria Folau in possession. Photo / Photosport

Pointing out that Silver Ferns goal attack Ameliaranne Ekenasio had likewise become a "point of difference" for the world champion New Zealand side, Alexander said the Diamonds had some defensive work to do should they wish to retain the Constellation Cup.

"I'm actually really proud of [Ameliaranne] in a funny way, but I don't like her beating us either," Alexander, who has coached the Diamonds for 101 tests, said.

"We've got some work to do in the defence end. I can't go into too much detail but we've got the two Swifts players that are there who play a really good split circle, we might need to trial that and give Maddy [Turner] an opportunity at some stage."

Both the Diamonds and the Silver Ferns depart for Perth today where they will be based for the week ahead of Sunday's final test.

Ameliaranne Ekenasio of the Silver Ferns lines up a shot. Photo / Photosport

Already having proved to be unfazed by the Australian home crowds, the Ferns look as confident as ever to retain the cup for the first time in seven years.

The Ferns have to win the fourth game in order to take the series though. If they don't, the cup will be decided by goal difference, in which Australia holds a six-goal advantage from their decisive win in Auckland.

The fourth test gets underway on Sunday at 3pm NZT.