Australian shooter Sharelle McMahon believes that her team have a better understanding of the Silver Ferns' defence, which they will be looking to exploit in tomorrow night's first test in Wellington.

Since the 2003 world championships, Australia have beaten New Zealand only three times in 11 games.

While counteracting Irene van Dyk has always been a problem for the Aussies, the reason they haven't been successful is more to do with their attack, in which they have struggled to get the ball through court and have then failed under the hoop. But there was a big improvement in the second test in July, which Australia won 48-38.

McMahon said that after analysing the Silver Ferns defence on video and working through the different defensive styles in training sessions "the penny seemed to drop". "We have been working very hard on finding the spaces within the New Zealand zone and the style of defence they set up.

"It is just a little bit of a change of what we are used to. We are trying to work the ball short and sharp but sometimes the space opens up long, it is just recognising when that happens. I think we did it really well in the second test - it definitely flowed a lot better than it has for a little while now - but there are things we can and will improve on."

New Zealand will be without defender Casey Williams, who was ruled out of the series yesterday with a knee injury.

Williams injured it in a warm-up game against the Australian Institute of Sport on Monday.

The Silver Ferns side was defence heavy so former international Julie Seymour, who was with the team as a training partner, was named as replacement.

McMahon acknowledged New Zealand's style of defence had changed in the nine years she had played them.

New Zealand used to stick to a zone defence, which was defending the space rather than the player, but had introduced a bit more one-on-one.

"Their zone isn't quite as structured as what it used to be," she said.

"I guess the zone is a little bit different to us so it is a matter of finding those spaces. The man on man, because we are more used to it, is something we can get around a bit easier."

As for her battle with Vilimaina Davu, or as the Australian supporters like to call her, the "smiling assassin", McMahon loves it. "We are both really fierce competitors - that makes for a great contest - and know that what happens on the court stays there."

Whether she will be squaring off directly against Davu tomorrow night is not known.

The Australian vice-captain, famous for netting the winning goal in the 1999 world championships, played at goal shoot, with Susan Pratley at goal attack, in the second test - which was effective.

But she could start at goal attack with Pratley or Catherine Cox at goal shoot.

"I prefer goal attack because I like to run around," McMahon.

"I feel a bit like a caged tiger at goal shoot at times. You are able to stand back and have a look at where those spaces are opening up."

McMahon has been guilty on occasions of trying to do too much at goal attack, something she is aware of.

"I guess it has probably been something that has been part of my game since I was a 10-year-old - I like running around.

"Over the years I have tried to take it out and have a little more structure in my game."