Series leaders Australia have suffered a blow in their women's and men's world sevens title battles with New Zealand, losing their semi-finals at the Hong Kong Sevens.

Australia's women lost 28-14, while the men went down 24-7 on Sunday, with both New Zealand sides going on to claim the title.

The Australian women at least enjoyed the consolation of finishing third in Hong Kong by winning their bronze medal match 24-21 against France after a terrific fightback.

But the men, with Michael Hooper in their ranks, lost 14-5 to Ireland in their third-place playoff.

In the women's series, after six events, New Zealand and Australia are now locked on 106 points at the top of the table.

But it was the Kiwis, winners of the previous two events, who proved too classy late as they pulled away against their perennial rivals after the scores were locked 14-14 at halftime.

Legendary winger Portia Woodman-Wickliff scored a crucial late try for the Kiwis, who went on to thrash USA 36-7 in the final.

Errors by the Australians proved costly in the second half, and Kiwi playmaker Jorja Millar ended any hopes of an Australian fightback as she scored in the dying seconds.

Australia had an edge in the first half after star winger Maddison Levi landed a heavy tackle on Woodman-Wickliff then raced away with the spilled ball to score.

New Zealand answered through Michaela Blyde before skipper Charlotte Caslick backed up to break from halfway and put Australia back in front 14-7.

But New Zealand again had an answer, with captain Risi Pouri-Lane making a brilliant break from halfway the level the scores going into the break.

Women's coach Tim Walsh was left admitting: "We made too many simplistic errors which proved costly in our overall outcome."

Australia's men's team also were swamped by their trans-Tasman rivals and defending Hong Kong champions.

New Zealand ran in two tries in each half while Australia struggled to crack a defence that conceded only four tries on the way to the semi.

Speedster Maurice Longbottom bagged Australia's only try, using sheer pace after a goal-line scrum to briefly put Australia ahead 7-5 with the conversion.

Longtime Wallabies skipper Michael Hooper debuted in sevens for Australia at the tournament, but the 32-year-old 125-Test veteran remained on the bench in the semi.

He did, though, get his first start against the Irish in the bronze medal match.

New Zealand went on to claim their 13th Hong Kong men's title by beating France 10-7 in the final.

It meant New Zealand moved up to fifth place in the series, one place ahead of the Aussies, with Argentina leading the way.