Canada picked up the winner's points when scoring in the last play of the final to beat England 7-5 and that lifted them to second, six points behind New Zealand's 72 points. The United States are third on 64 points and Australia fourth with 56 points.
The Black Ferns Sevens denied Australia ball for all but 20 seconds of the first half and ran out to a 34-0 lead before their opponents were able to string a move together.
It was a necessary win for the New Zealanders who earlier lost their quarterfinal to the United States 19-26. They last lost a quarterfinal in Dubai in 2017, and that was to the USA as well. In order to qualify for the fifth and sixth playoff they had to replay Russia, with whom they had drawn 17-17 in pool play, but this time they won 36-0.
Your series standings after four rounds on the HSBC World Rugby Women's Sevens Series.
Against the Russians next up, there was complete dominance from the New Zealands with Ruby Tui and Tyla Natha-Wong scoring in the first half and then they cut loose in the second half with Shakira Baker, Sarah Hirini, who scored twice and Faleafaga all crossing in the 36-0 win.
The playoff victory over Australia showed New Zealand at their most potent. They dominated the kickoff and restarts with Australia unable to secure one during the first half.
Running amok with such a wealth of position, the Black Ferns Sevens unleashed backhand passes and offloads at speed to fully stretch their trans-Trasman rivals. Hirini scored the first off a Tui backhand and then Faleafaga showed her speed in getting the ball down in the corner in the tack.
Almost straight away Alena Saili scored on the opposite wing, courtesy of two backhand passes. Then Hirini fed Faleafaga with room to move on the right. She fended off three Australians before Hirini came through in support to score her second.
Tui had some reward for her work when scoring New Zealand's fifth try on the back of some fine work by Stacey Waaka.
At the start of the second half Australia's kickoff didn't go 10 metres and in the resulting play Nathan-Wong kicked ahead, regained the ball and outstripped the defence to claim a try.
The failed restart by the Australians may have proven costly as they came home with a wet sail scoring four unanswered tries through Mahalia Murphy, Emma Sykes, Charlotte Caslick and Emma Tonegato, her 100th world series try. Three of the tries were converted, but their bid ran out of time.
The fifth leg of the six-leg series will be played in Langford, Canada on May 11-12.
??#Kitakyushu7s pic.twitter.com/73fjkUQf91— Black Ferns (@BlackFerns) April 21, 2019