"We're not really chasing any sort of result, what we're really working hard on is to improve. These games are not like your normal international friendly, so we do need to get results, but we don't put any pressure of score-lines on the players."
The Ferns are missing first-choice striker Hannah Wilkinson, who is sidelined with a long-term knee injury, but are otherwise at full strength.
Captain and centreback Erceg said she has become used to the conditions over the years and is now better prepared for the island heat.
"It's really a different kind of heat here. It's incredibly humid and dry and you don't really ever want to go outside if you don't have to. We need to keep hydrated because the game is in the heat of the day, so it will be tough but we just have to get on with the job at hand."
In their last four games against Papua New Guinea the Ferns have scored 29 goals and conceded 0, but Erceg said she won't struggle with finding the motivation to put in a big performance.
"You could look at the score lines and think it's a walk in the park, but it's the Olympic Qualifiers and the hunger and desire to get back to the Olympics really drives the motivation. Also I don't know how many major tournaments I will have left and our team is always looking for improvement no matter what games we play, so it's not hard to find motivation."
After the two-legged playoff the Ferns have the Algarve Cup in Portugal in March with group games against Brazil, Russia and Portugal and are also targeting games in the April and June Fifa windows.
Match 1
Papua New Guinea v New Zealand
Saturday 23 January, 2pm (Saturday 23 January, 5pm - NZ time)
PNGFA Academy Pitch, Lae, Papua New Guinea
Match 2
New Zealand v Papua New Guinea
Tuesday 26 January, 7.30pm
QBE Stadium, Albany, Auckland