Six remain unbeaten in Vegas

New Zealand, Samoa, Fiji, South Africa, Kenya and England all remained unbeaten after the opening day of action at the United States leg of the IRB Sevens World Series, in Las Vegas on Friday.

Of those sides, New Zealand, Samoa, Kenya and England are mathematically - already - guaranteed a place in the Cup quarterfinals.

In a changed format for the USA leg of the Series, each of the 16 teams played two of their three pool matches on Friday evening at the Sam Boyd Stadium. On Saturday they will play their remaining pool match and then a quarterfinal in either the Cup or the Bowl, leaving the climax of the knock-out competition for Sunday.

"We are delighted with our first 'Friday night football' at the US Sevens," said US Sevens Tournament Director Dan Lyle.

"These international Sevens players are incredible athletes and they've already laid on some spectacular action for the fans," he added.

After the first four rounds of the World Series - in Australia, Dubai, South Africa and New Zealand - the Kiwis lead the overall Series with 73 points, ahead of Fiji on 70. England lie third on 64 overall three ahead of South Africa in fourth.

We take a look at all of Friday's pool action:

Pool A:
(New Zealand, Samoa, Australia, Japan)

World Series leaders New Zealand maintained their 100 percent record on day with a 42-5 victory against Japan and 31-5 defeat of rivals Australia, and entered the Cup quarters after Samoa's 19-15 victory against Michael O'Connor's side in the day's final match.

The nine-time Series champions have not won the US Sevens since 2008 in San Diego but began their campaign with a 31-5 victory against Australia.

Two Tomasi Cama tries in the second seven minutes ensured New Zealand defeated their trans-Tasman rivals with Mark Jackman also scoring twice in the match and Lote Raikabula adding the first for Gordon Tietjens' side.

In their match against Japan two Frank Halai tries, Johnathan Malo's first two tries on the World Series and 15 points from Mark Jackman helped Gordon Tietjens' side to a second victory.

Former World Series champions Samoa also recorded a victory in their first match with a 33-0 defeat of Japan thanks to two tries from Afa Aiono and they now face Australia in the day's final match and will play New Zealand in the Pool A decider on day two.

Results:
Samoa 19-15 Australia
New Zealand 42-5 Japan
Samoa 33-0 Japan
New Zealand 31-5 Australia

Pool B:
(Fiji, Canada, Argentina, United States)

Fiji became the first side to win both of their first two matches after a 33-19 defeat of the hosts to an earlier 14-12 victory against Argentina.

Eighteen points from Metuisela Talebula assisted the Fijians in their win against Al Caravelli's side, whilst they came from 12-0 behind to eventually beat two-time US Sevens champions Argentina 14-12 in an enthralling opening match thanks to tries from Nemani Nagusa and Waisea Nayacalevu.

Taylor Paris' late try snatched a 17-12 victory for Canada against rivals and hosts US in the second match of day one.

Last week's Cup quarterfinalists came from behind twice to secure victory but were unable to beat Argentina in their second match, conceding two tries to Francisco Merello in a 19-12 defeat.

Results:
Canada 12-19 Argentina
Fiji 33-19 United States
Canada 19-12 United States
Fiji 14-12 Argentina

Pool C:
(France, South Africa, Wales, Uruguay)

Cecil Afrika scored a hat-trick to take his day one try tally to five in South Africa's 29-12 victory against reigning World Cup Sevens champions Wales.

Afrika earlier scored his first two tries of the tournament as he helped Paul Treu's side to a 33-0 victory against Uruguay. The defending US Sevens champions scored three other tries through Cornal Hendricks, Frankie Horne and Bernado Botha, scoring his 30th World Series try.

An Alex Walker conversion proved the difference for Wales in their 14-12 victory against Dubai Sevens runners-up France. Trailing 7-12 after tries from Paul Albaladejo and Julien Jane, Lee Williams raced away to cross the line before Walker converted to take the win.

Uruguay narrowly missed out on an upset against France, eventually losing 19-21. Two Felipe Berchesi tries and one from Guillermo Lijtenstein gave them a 19-14 lead but Terry Bouhraoua's try and Thibaut Zambelli's conversion snatched a late victory for France.

Results:
South Africa 29-12 Wales
France 21-19 Uruguay
South Africa 35-0 Uruguay
France 12-14 Wales

Pool D:
(Kenya, England, Scotland, Brazil)

England booked their place in the Cup quarters with a dramatic 12-7 victory against the Auld Enemy Scotland. Having scored their first try Dan Norton was then sent off, but a Christian Lewis-Pratt try with seconds remaining ensured Ben Ryan's side maintained their 100 percent record on Day One.

Currently third in the Series they opened up with a 29-5 victory against Brazil thanks to a Norton hat-trick. Brazil were making their first outing on the world stage since 2002 and are building towards the hosting of Sevens Rugby's first Olympic event, in Rio in 2016.

Collins Injera also scored a hat-trick against Brazil as Kenya recorded a 38-0 victory against Martin Schusterman's side adding to an earlier 17-14 victory against Scotland to also progress to set up a pool decider with England on day two.

Two Humphrey Kayange tries and Injera's first of the day helped the African side come from 0-7 down to beat Graham Shiel's side in the opening Pool D match of day one.

The Kenyans, with brothers Kayange and Injera back in harness, are showing something near their best form and picking up where they left off in Wellington.

For the Scots, captain Colin Gregor is the only player on show to have started 25 matches - all of his team's games - this season.

Results:
England 12-7 Scotland
Kenya 38-0 Brazil
England 29-5 Brazil
Kenya 17-14 Scotland