Kiwis wing Dallin Watene-Zelezniak is in doubt for the knock-out match at Wellington Regional Stadium after suffering a knee injury.
The 22-year-old crossed for his first try in a Kiwis jersey to open the scoring for the Kiwis in the 20th minute and made several strong carries to help New Zealand get off their own line.
"Dallin's got a bit of a knock to the knee so we'll see him throughout the week," said Kidwell.
Meanwhile, Kidwell admitted his team needed to improve if they were to get past a Fijian side that has gone unbeaten to finish top of Pool D, after overcoming Italy 38-10 on Friday.
With five-eighth Jarryd Hayne directing play and fullback Kevin Naiqama and wing Suliasi Vunivalu also in top form the Kiwis are wary of Fiji's potent attack.
"They can score from anywhere and have a very strong back-five, and they're in form, we have to make sure we're on our defensive game," Kidwell said.
"Obviously Jarryd Hayne, he loves these big games and big moments.
"There are some areas we need to improve on and (the players) were honest about those areas in the sheds and with the little things that make up the big picture.
"Kick pressure at the right times, making sure we complete our sets and get to our kicks, so we can get back into the grind of the game."