It was a disappointing end to what had been a phenomenally good start but it's often difficult to maintain standards when a game has already been won.
"I was pleased with the performance, or certain parts of the performance,'' coach Stephen Kearney said. ``I thought the lads started really well and what we worked on all week about being really focused and disciplined about our performance, they were certainly that.
"With the second half we made a few changes at halftime and that probably threw the mix of the group a little bit. I didn't think the second half was so good but it was pretty difficult when you get to that type of scoreline.''
There got there thanks to some class from Sonny Bill Williams. By halftime he had a hat-trick of tries - although he nearly botched another one like he did against Samoa getting dangerously close to the dead-ball line - as well as 13 tackle breaks, four linebreaks, seven offloads, one try assist and 119m in 14 runs.
It was what the capacity crowd at Headingley had come to see, although they might have also enjoyed a closer contest.
Papua New Guinea had no answer in the opening period but the Kiwis rarely lifted their foot off the pedal. They scored some good tries, and Roger Tuivasa-Sheck showed his dancing feet as he scored a double, but they did the simple things well - the things that win World Cups - completing 95 per cent of their sets in the first half.
Their first mistake was when Shaun Johnson hit the upright with a conversion attempt on the half hour from right in front of the posts. It was a shame for Johnson, whose goalkicking has improved enormously this year and had been exemplary until then, and prompted calls from the good crowd of, `who are ya?'.
The biggest roar of the night came when Dion Aiye scored 68 seconds after halftime. It wasn't really a concern for the Kiwis, who hadn't switched on after the break, but what was disconcerting was seeing Leuluai struggling to keep up as the Kumuls attacked his edge.
He had just come onto the field for his first taste of the World Cup after battling a groin injury. Kearney had been keen to not only test the groin but also see how he went playing alongside Kieran Foran in the halves.
Leuluai's World Cup looks over now and the Kiwis' attempts to get approval to use a drug prohibited by the UK Anti-Doping agency seem academic.
"It doesn't look good for him but we will see how things pan out,'' Kearney said. ``It's a real shame for him because I know he would have added a great deal to the group.''
It leaves the Kiwis short of backup should anything happen to Johnson, Foran or hooker Issac Luke - and that is a worry.
Vatuvei was also replaced at halftime with a recurrence of a knee injury and Hoffman strained his AC joint after falling on it awkwardly although Kearney is hopeful the pair are fit for next weekend's quarter-final.
Injuries were probably the biggest concern in a game like this. Set-pieces can be tidied up in training but the Kiwis can't afford to lose crucial players because the real business starts next weekend.
New Zealand 56 (Sonny Bill Williams 3, Roger Tuivasa-Sheck 2, Dean Whare 2, Bryson Goodwin, Frank-Paul Nu'uausala, Elijah Taylor tries; Shaun Johnson 8 gls) Papua New Guinea 10 (Dion Aiye, Wellington Albert tries; Francis Paniu gl). HT: 40-0.
