New Zealand were largely untested in making a winning start to their Wellington sevens rugby tournament campaign today.

After a scrappy, disjointed effort to down Scotland 29-12 in their opening match, the hosts put in a more accomplished display to overwhelm Papua New Guinea 45-0.

They are to face a pool-deciding showdown late tonight against Argentina who struggled to subdue Papua New Guinea and made hard work out of beating Scotland.

Coach Gordon Tietjens has a history of unearthing stars at this tournament and in the hot-stepping Buxton Popoalii he may have added another to that list.

The fullback left Wellington for Otago in an attempt to get more game time and showed capital fans what they were missing out on with an elusive display.

He jinked his way through Scotland's defence seconds after entering the fray and then again showcased his sidestep in crossing for two tries against Papua New Guinea.

The hosts, who have not won the tournament since 2008, started the tournament slowly against Scotland, but emerged with the win scoring five tries to two.

Playmaker Tomasi Cama and flyer Frank Halai crossed in the first half, before emerging talent Declan O'Donnell stepped past two defenders to extend their lead after the resumption. Halai added his second before Popoalii crossed late on.

But Scotland managed to expose some defensive shortcomings in the inexperienced New Zealand lineup to grab second-half tries to Andrew Skeen and Michael Fedo.

The Shane Howarth-coached Papua New Guinea posed no such problems and New Zealand enjoyed a seven-try romp with David Raikuna, DJ Forbes, Solomon King, Scott Curry and Toby Arnold adding to Popoalii's brace.

Elsehere, South Africa's Renfred Dazel was left with egg on his face after his blunder allowed France to cause the biggest upset of the day.

With the fancied South Africa leading 12-7, Dazel seemed destined to score a try but stepped out of bounds in the in-goal area. With time up on the clock, France's Renaud Delmas scooted through to dot down under the posts to give them an unlikely 14-12 win.

It was a dramatic turnaround for France who were soundly thumped 42-0 by Fiji in their opening game.

World series leaders England flirted with an embarrassing defeat to the Cook Islands before a second half rally saw them emerge with a 21-17 win.

The Cook Islands stunned England to take a 17-0 lead into the break after tries to Turori Matutu, Sailosi Nagi and Koiatu Koiatu.

But England, energised by the guile of Ben Gollings and two tries to the pacy Mat Turner, dominated the second half to emerge with their reputation intact.

Defending champions Fiji were looking in ominous form and have yet to concede a point in the tournament. They were clinical in dispatching France and followed that with an easy 38-0 over Canada.

Kenya were left to reflect on what might have been after giving Samoa a big fright and then were left querying refereeing decisions which saw Australia score a disputed try to edge past them 21-19.