BlitzBoks and Kiwis through to quarters already

Four spots are still up for grabs with the all-important and decisive third round of pool matches taking place on day two before the quarterfinals in Las Vegas, with more record crowds expected after a new day one attendance record of 18,441 turned out.

In Pool A, back to back champions from Wellington and Sydney New Zealand picked up where they left off in round five of the Sevens World Series, scoring 80 points and conceding just one try in wins over Russia and Portugal, the same sides that tasted defeat to Benjamin Ayimba's Kenya.

Humphrey Kayange scored his 150th and Kenya's 1,500th sevens try in their win over Russia while Collins Injera scored three times on day one to move within three tries of Ben Gollings and second place in the all-time leading try scorers behind Santiago Gomez Cora.

South Africa also won both of their matches on day one with Bryan Habana returning to rugby sevens after a 12-year absence to score one of the tries of the day as the BlitzBoks opened up with a 33-7 win over Canada before Seabelo Senatla scored a hat-trick in their 36-7 win over Wales, taking his tally for the day to five and 30 for the season.

Canada bounced back from their defeat to Neil Powell's side to draw 26-26 with the hosts USA with both sides aiming to take the second qualification spot from Pool D.

The hosts won their opening match 19-12 against Wales before the enthralling draw with North American rivals and next week's hosts Canada. Having led 26-7 thanks to two superb tries from Perry Baker, Conor Trainor, Nathan Hirayama and Phil Mack, playing in his 50th tournament, drew the scores level to leave it all to play for in Pool D.

Elsewhere Pool C is wide open after defending Las Vegas champions and current series leaders Fiji lost to Samoa in their opening match of the day, their first defeat in a pool match since the 2014 London Sevens, before beating France 42-12.

Samoa had the chance to qualify for the Cup with a victory over Argentina but were beaten 25-12 with Bautista Ezcurra scoring twice in the win. Los Pumas' win was their second of the day having earlier beaten France but must wait until day two to confirm qualification for the last eight with a match against Ben Ryan's Fiji.

Australia were the only other side to win both of their matches on day one, beating Scotland and Japan in Pool B to secure qualification to the last eight.

England left it late to snatch a 19-19 draw with Japan who had led 19-5 with Jack Wilson and Phil Burgess scoring the tries to secure the draw before they proved too strong for Scotland.

All the Day One results:

New Zealand 42-7 Portugal

Kenya 24-21 Russia

South Africa 33-7 Canada

United States 19-12 Wales

Fiji 24-28 Samoa

Argentina 26-7 France

Australia 26-0 Scotland

England 19-19 Japan

New Zealand 38-0 Russia

Kenya 38-0 Portugal

United States 26-26 Canada

South Africa 36-7 Wales

Fiji 42-12 France

Argentina 25-12 Samoa

Australia 35-5 Japan

England 14-24 Scotland

Source: @WorldRugby7s