Fiji's Hamilton Sevens title defence comes to a shock end after defeat to Argentina

Australia's men have earned a shock berth in the semi-finals of the sevens world series tournament in New Zealand, helped by Fiji's title defence coming to a clattering halt.

Santiago Alvarez. Source: Photosport

The Australians topped their pool on points differential after beating Samoa 33-19 in Hamilton on Sunday and then watching on wide-eyed as Argentina stunned two-time tournament winners Fiji 26-10.

Only the pool winners advanced, leaving Australia to next face New Zealand while England and France were to meet in the other semi-final.

It was just reward for Tim Walsh's team, who were excellent in thumping Argentina on day one before a narrow loss to Fiji.

However one black mark emerged from the Samoan victory, with star back Ben O'Donnell suffering what appeared to be a serious knee injury.

A near-certain Olympic selection if fit for Tokyo in July, O'Donnell was playing his first tournament of the season after undergoing surgery to remove a plate from his arm.

The Australians put aside the early departure of their star back with an impressive display against the Samoans, highlighted by a hat-trick to Josh Turner.

The former New Zealand under-19 rugby captain crossed twice in the first half to put his team 14-12 ahead at halftime.

Joe Pincus, who replaced O'Donnell, extended the lead before Turner and Maurice Longbottom bagged late tries after Samoa had reduced the deficit to two points.

Australia, who have not won the New Zealand tournament in 20 years of trying, can considerably boost their world series standings.

They arrived in ninth place after two rounds, well behind co-leaders New Zealand and South Africa.