Series leaders New Zealand raced out of the gate on the opening day of the US leg of the IRB Rugby Sevens World Series, the fifth of the championship’s nine rounds.

New Zealand, who arrived off a home triumph in Wellington last weekend, defeated Japan 42-5 and Australia 31-5. They secured their Cup quarter-final berth after Pool A rivals Samoa beat Australia 19-15.

Kenya, England and Samoa also secured their Cup quarter-final spots on a day when all 16 teams played two pool matches apiece – with pool play to finish on Saturday.

New Zealand, nine-time World Series champions, have not won the US leg since the 2008 edition in San Diego.

They launched their campaign with the victory over Australia, which included two Tomasi Cama tries in the second seven minutes. Mark Jackman also scored twice.

Jackman had 15 points in the win over Japan, which saw two tries apiece from Frank Halai and Johnathan Malo.

Samoa also opened with a win, defeating Japan 33-0. They will battle New Zealand in the Pool A decider on Saturday.

Fiji and reigning US champions South Africa were also unbeaten on the day.

Fiji, who arrived in Las Vegas trailing Series leaders New Zealand by three points, 73-70, rallied from 12-0 down to defeat Argentina 14-12 and posted a 33-19 victory over the United States in Pool B.

In Pool C, Cecil Afrika scored a hat-trick to take his try tally for the day to five in South Africa’s 29-12 victory over Wales. Afrika had scored two tries in a 33-0 victory over Uruguay.

Pool D rivals Kenya and England both booked Cup quarter-final spots. England claimed their berth with a dramatic 12-7 victory over Scotland.

After scoring England’s first try Dan Norton was sent off, but a try from Christian Lewis-Pratt in the waning moments kept England unbeaten after their 29-5 victory over Brazil.

Collins Injera scored a hat-trick in Kenya’s 38-0 victory over Brazil after a 17-14 victory over Scotland.

Kenya and England will play on Saturday to decide the winner of the pool.