Rookie winger Ruby Tui has scored a try double, but the Black Ferns turned on a dominant defensive display to dismiss Canada 28-0 in their Pacific Four clash at Waitākere.
With a stiff breeze at their backs through the first half, the NZ women led just 6-0 at halftime, an advantage that didn't seem enough turning into wind against the world No.3 team, who had piled 36 points on the United States six days earlier.
But the reigning world champions showed their grit, keeping their rivals off the scoreboard over the closing 40 minutes and piling on four tries of their own, including a pair to the Olympic sevens star on her first 15-a-side campaign for her country.
The Ferns had to negotiate the challenge short-handed for 20 minutes, after prop Tanya Kalounivale and No.8 Kaipo Olsen-Baker were yellow-carded either side of halftime.
New Zealand managed just two penalties from first-five Hazel Tubic in the first half and struggled for continuity, as the Canadians brought a physical approach to the contest.
Ferns rugby director Wayne Smith had made seven changes to the starting line-up that faced Australia on Monday, giving his entire squad a chance to press for World Cup selection later this year.
Kalounivale sat out the final 10 minutes of the half, after her third offside infringement at a ruck, leaving her team to reshuffle their scrum, but Canada could not capitalise before the break.
Still, the six-point lead seemed insufficient under the conditions and the Kiwis braced themselves for the onslaught.
Soon after the restart, they gained some more breathing room, when powerful winger Aeysha Leti-I'iga ran a punishing line off an attacking lineout and when the ball shifted across the field, Tui chipped ahead and gathered the kindly bounce to score her first international 15s try.
When Olsen-Baker departed for a high tackle, the Canadians threw everything at their opponents, but were repeatedly held at bay. Still a player down, the Ferns worked another lineout move that saw prop Amy Rule brought down short, but lock Maia Roos following up to score.
Restored to full quota, New Zealand had their third try, when teenage debutant Sylvia Brunt broke from her own half, Leti-I'iga took the movement to the tryline and forward Chelsea Bremner plunged over from the ruck.
From the kickoff, centre Amy du Plessis found space down the left and sent Tui away for her second, as the speedster wove her way through a tiring defence.
The result leaves New Zealand as the only unbeaten side remaining in the four-way tournament, with the Americans looming next Saturday at Whangārei.
Black Ferns 28 (Tui 2, C Bremner & Roos try; Tubic 2 penalties, Demant conversion) Canada 0
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