New Zealand forward Jared Waerea-Hargreaves on Thursday said the Kiwis would not be rattled by Papua New Guinea's physical approach in Saturday's Four Nations clash in Rotorua.

Waerea-Hargreaves noted that while the Kumuls lost 42-0 to Australia last weekend in Sydney, the host nation had to endure some crunching tackles from their hard-hitting opponents.

"They showed against the Aussies that they can upset them quite a bit," he said.

"We're looking forward to the contest. It's going to be very physical."

Waerea-Hargreaves said New Zealand could not afford to be drawn into a slugfest against Papua New Guinea as the Kiwis seek to build on a 24-10 win over England in the tournament opener.

"Their defence is awesome and they are very keen to get out there and put a few shots on," he said.

"We can't fall into the shot-for-shot. We just have to keep to our game-plan."

He added the Kiwis must remain switched on for the entire game as the Kumuls, rank outsiders in the tournament, have nothing to lose, giving them the freedom to throw the ball around.

"They're the tough ones," the 21-year-old said. "We're expected to win and they're the underdogs.

"They're going to be coming out fired up and we just have to come out and get on top of them from the start."

Australian referee Ben Cummins was called in to officiate the match on Thursday after England's Richard Silverwood injured his leg during training.

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