AIX-EN-PROVENCE (Reuters) - New Zealand will have little problem stepping up a gear for the knockout phase of the World Cup after a string of easy victories in the pool games, according to loose forward Jerry Collins.

The 26-year-old, who has been one of the team's most impressive performers in the tournament, said the knowledge that a bad performance could mean elimination was more than enough incentive for the team to improve.

"It is not a concern," Collins told reporters at the team's training base in the southern French town of Aix-en-Provence. "After this week it could all be over the following week and you might be talking about us going home.

"So for me after Saturday it's a question of who gets it right on the day... You can have the best form leading into the playoffs, but they are one-off games.

"You can be the worst performing team going into the quarter-finals... and end up playing three good games and that's all that matters.

"You can be the best all year, but if you lose the one game that counts you have to wait another four years to get a shot."

The All Blacks have won all three of their pool games with considerable ease, crushing a much-fancied Italy side 76-14 in their opening match, racking up one of the highest scores in World Cup history with their 108-13 win over Portugal and then inflicting a 40-0 whitewash on Scotland at Murrayfield.

Collins said the team would be using its final pool game against Romania on Saturday to iron out some of the uncharacteristic errors against Scotland last weekend.

"We are trying to play some footie and at the moment the little things are letting us down.

"But I'd say this Saturday will be much better than last Saturday. We really need to start kicking into gear and start working towards a quarter-final. Saturday is a big test for us."