Highly-rated New Zealand forward Sika Manu's World Cup is over following concerns he could require surgery should he further damage his cracked right eye socket.

A shattered Manu was given the news after x-rays confirmed an undisplaced fracture making it too dangerous for him to have any contact play for up to two months.

With strike forwards Sonny Bill Williams and Frank Pritchard both unavailable, the 21 year-old, 108kg Wellington born Manu was seen as a player who could step into a similar line breaking role.

He scored a wonderful try against Australia last weekend, bursting onto a Benji Marshall inside pass before steaming across the tryline at high pace.

"He's not a big talker but he went pretty quiet," said Kiwi team doctor Simon Mayhew after Manu was given the disappointing medical update.

"We've talked about it a few times and he understands the rationale behind not taking any more risks. I wouldn't say he's happy, but he understands."

One player who was happy was halfback Thomas Leuluai who has retained his No.7 jumper after a less than impressive effort against Australia's Johnathan Thurston last weekend.

Leuluai was heavily criticised for not getting involved and blamed for New Zealand's uninspiring performance.

But Kearney said he was always going to stick with him against PNG and for the tournament.

"I don't know if it's maintaining faith - he was always going to be selected," Kearney insisted.

"That wasn't an issue. We were playing against the current world champions so they were always going to put our halves, and the whole team, under pressure at certain stages.

"At this stage we think he's the best man for the job and we're confident he's going to get the job done for us."

Kearney said Leuluai and five-eighth Marshall, who also copped some flak, had limited opportunities to ply their trade in Sydney.

"It's hard to work off the platform where you're always on the back foot. Statistics showed that," he said.

"We attacked Australia's goal line seven times while they attacked ours 18 times.

"The times we were down there, Benji and Thomas put some good plays on which were effective. We got over the line twice, and had one disallowed (to Jerome Ropati)."

Kearney has laid down the law about ill discipline which helped Australia get the jump on them.

"That certainly is an issue, our discipline, even though the penalty count was only seven," he said after the team trained in the Gold Coast heat.

"I don't mind the lads giving away penalties if they're in a position where they're going to get scored against on the next play (to prevent a try).

"But when a side's coming out of their half and we give them double-ups and they go 80m without even having to work for it, that irks me a bit."

Kearney has made three key changes which include Setaimata Sa replacing Manu in the second row and David Fa'alogo coming onto the bench.

Exciting youngster Krisnan Inu takes over from suspended centre Steve Matai while livewire hooker Issac Luke has won a recall to the bench at Dene Halatau's expense.

Damaging winger Manu Vatuvei is battling a shoulder injury but is expected to play.

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