New Zealand assistant coach Ian Foster said the All Blacks are more consumed by ensuring they raise their game ahead of the Rugby World Cup quarter-finals rather than considering who they would prefer to face in the last eight.

The world champions have already qualified for the knockout stages of the tournament in England by winning all three of their Pool C matches.

Steve Hansen's side have one pool match to come against Tonga at St James' Park on Friday, when they will be expected to maintain their 100 per cent record and secure top spot.

New Zealand will face either Ireland or France in the quarter-finals and Foster stated on Thursday that the World Cup favourites will be ready to take on whoever comes their way.

"We have enough to worry about ourselves without worrying about things we can't control," said Foster. 

"Yes, we'll spend energy looking at both teams but who we want to play? We'll just wait and see."

Ma'a Nonu will make his 100th international appearance for the All Blacks in Newcastle, in a side which features six changes to the line-up which started the 43-10 defeat of Georgia last week.

Foster said New Zealand already have a team in mind for their game against either Ireland or France but that is not set in stone.

He added: "We've got a plan but we'll take this Tonga game first and foremost. We'll make that decision at the weekend. We've got a plan with the ability to adapt."

New Zealand have not been at their brilliant best in the tournament so far and Kieran Read, captain against Tonga in the absence of the injured Richie McCaw, knows there is room for improvement.

"It's important we take a step up in what we've been doing. Every week we prepare well." the number eight said.

"We've been improving throughout this World Cup. This week it's Tonga, they'll put us under pressure in certain areas."