Pama Fou, 21, scored two tries for the fluorescent green Thunderbolts in their opening pool match of the first HSBC Sevens World Series at Skilled Park.

Not bad for a young man who was left heartbroken two years ago when persistent shoulder problems forced the then-Queensland Academy of Sport athlete to give up his dream of playing volleyball for Australia.

"It took me a fair while to get over the sport but I can't waste these days being a sook about [it], I'm here in an IRB tournament," Fou said.

Australian skipper Ed Jenkins and his deputy Jacob Taylor, two of the squad's most experienced players, scored one try each, as did Danny Routledge.

Jenkins also starred in the Thunderbolts's second pool game against the United States, scoring twice.

The Aussies survived an early scare from the quick and tough Americans to defeat them 22 points to 7.

Fou was played off the bench in the second half and displayed the same speed that impressed against Japan, but also showed he had work to do in defence, allowing American Miles Craigwell to slip past and run the length of the field before Lewis Holland pulled him up just in time.

Greg Jeloudev and Junior Rasolea scored tries but the Taylor failed to convert twice, leading coach Michael O'Connor to declare kicking the Australians's main weakness.

"I'm not very happy [with the kicking]," O'Connor said after the game.

"It's just across the board, it's not something we do well in Australia."

A win against the USA put Australia into the quarter finals, O'Connor said.

"Two wins so I'm happy, it more or less means we're through to the quarters tomorrow ... it's always a relief to know you're in the top competition going into knock-out day," he said.

In the earlier game, Taylor made three conversions and Junior Rasolea kicked the fourth, stamping Australia's dominance over a nervous Japan line-up that appeared to quickly fatigue.

Fou also battled nerves, he said. This was the former Aucklander's Sevens debut and he was nervous about taking his first hit.

But two years playing rugby seems to have converted Fou to the seven-a-side format, who came to Australia when he was 17.

"I like to think Sevens is my main forte because I get more space and speed is my forte," he said.

O'Connor praised his new recruit after the game but asked him to step out in front of the line more instead of hanging back, Fou said.

New Zealand also impressed in the afternoon's play, trouncing an inexperienced Kenyan side 26-5 and punishing Niue in their second pool A game,

Pool D produced the day's thriller. Wales scored in the dying seconds of their game against Scotland to beat their opponents 14-12.

Tournament heavyweights South Africa, who meet Australia later tonight, were spooked by the USA but managed to hold out for a 17-12 win.

Playmaker and IRB Sevens Player of the Year Cecil Afrika made his return from injury in the second half, making all the difference for the young Springboks.

Australia plays the USA at 7.15pm (AEDT) and then meets South Africa in the final pool B game at 10.36pm (AEDT).

Georgina Robinson travelled to the Gold Coast courtesy of HSBC.