The Black Ferns sevens have thrashed Australia 31-14 in the final of the Cape Town sevens tournament this morning.

It was a near flawless performance in the heavy rain by New Zealand, who were missing the injured Niall Williams and with veterans Sarah Hirini, Stacey Fluhler and Theresa Fitzpatrick remaining at home.

The Olympic champions retained and used possession far better than the Australians, who were in a hot streak of form after winning in Dubai last weekend, with Tyla Nathan-Wong named player of the match for her two tries and relentless workrate.

They cruised to a 21-0 lead with Shiray Kaka over first and Nathan-Wong scoring a double – all converted by Nathan-Wong.

As Australia began the second half facing an uphill battle, Michaela Blyde burst through two would-be defenders to score for New Zealand, with the Aussies finally replying through Madison Ashby from distance.

Kelly Brazier stopped any notion of an Australian comeback with a try with just under two minutes remaining when Nathan-Wong stole the ball from the Australian halfback after a defensive scrum.

Demi Hayes then went over for little more than a consolation try for Australia.

“An epic performance by the team,” Nathan-Wong said afterwards. “This week has been a bit of a grind for us… we didn’t perform like we wanted but in the final it all came together.”

Head coach Cory Sweeney said: “It’s been hard to put into words. This group has stood up and to do that in a final, I’m really proud, it’s awesome.

It’s a special moment for us today with an 18 month lead in to the next Olympics.”

New Zealand qualified for the final after a run of perfect pool play results, including a come-from-behind win over Fiji, and respective quarter-final and semifinal wins over Canada (50-5) and Ireland (14-7).

In the men's final played in driving rain with large puddles on the field, Samoa beat New Zealand 12-7 after scoring a last-minute converted try.

Brady Rush had put New Zealand ahead with four minutes remaining and the Kiwis were playing at the right end of the field, but a long kick and chase by Samoa finished with a debatable ruck penalty awarded to them and they capitalised via Vaa Apelo Maliko.

The USA shocked hosts South Africa 22-14 in the bronze medal match, with the USA women also winning bronze after beating Ireland 20-12.