After holding a commanding 16-2 lead at the break, the Kiwis concede they shot themselves in the foot in losing 28-22 to Tonga in their World Cup Pool B clash on Saturday.
Through the opening 40 minutes at Waikato Stadium, New Zealand showed periods of defensive grit to deny Tonga with a number of goal-line stands, while looking polished in attack with an 83 per cent completion rate while making five line breaks and crossing for three tries.
But for all their hard work in the first half, the Kiwis hardly fired a shot in the second, coughing up seven errors as they were outscored five tries to one, with halfback Shaun Johnson frustrated at the self-inflicted blows his team delivered.
"Having a handy lead at half-time and coming out and letting that slip away, we probably blew it," Johnson said.
"We shot ourselves in the foot a few times there with us being a bit flustered at times and probably looking to overplay and not just getting into the work we had spoken about all week.
"In that sense it's very frustrating, but credit to Tonga.
"There were a couple of bad plays on my behalf at back end of the game which I am not too happy about… we probably shouldn't have found ourselves in that position in the first place to be honest."
Poor defensive plays contributed to Tonga's opening two tries, with Dallin Watene-Zelezniak failing to make a play at a bomb on his own line, which was instead claimed by David Fusitu'a for a try, before New Zealand were caught ball watching on Fusitu'a second effort 11 minutes later.
There were also key errors coming of out yardage, none more notable than Russell Packer's decision to throw a cut-out pass inside his own 40, which was intercepted by Tuimoala Lolohea for a try just after the hour.
Captain Adam Blair admitted his side's own poor discipline, and the pressure Tonga applied, forced New Zealand into a number of unforced errors.
"We weathered the storm early, we put them in a grind and came out on top in that first half. I think we let ourselves down in the discipline areas that we are normally really good at and have been in this tournament," Blair said.
"That then forced us to try and play some footy and cause a few errors.
"In the end they just put enough pressure on us, we made a few errors and they scored some points, and it's hard to stop a team when they are running forward with the calibre of players they have got."
The loss means the Kiwis will now have to face unbeaten Fiji in the quarter-finals on Saturday in Wellington.
