BlitzBoks and Kiwis cruise in HK
Sevens World Series leaders South Africa and defending Hong Kong champions New Zealand recorded first round wins on day one.
The Hong Kong leg is Round Six of the Series.
Cecil Afrika, Seabelo Senatla, Albertus Smith and Werner Kok scored tries for the BlitzBoks, who have never won the Hong Kong title.
It saw them beat Argentina 24-0.
Former Sevens Players of the Year DJ Forbes and Tim Mikkelson scored for Gordon Tietjens' New Zealand side in a 21-7 win over Scotland.
Fiji and Australia also impressed in their first outing, beating Samoa and Portugal respectively, ensuring the top four teams in the overall standings got off to a solid start at the 40th anniversary edition of the Hong Kong Sevens.
Twenty-eight nations took to the field in front of 38,642 fans on Day One of the three-day event - as 12 teams joined the main Series competition in the World Series qualifier.
Belgium, who were making their series debut, put up a gallant fight going down 12-28 to Canada, while the United States fought back from 0-14 down at half-time against Kenya to win 21-14 - after Make Unufe, Carlin Isles and Danny Barrett scored unanswered tries in the second half.
England and France also recorded wins on day one.
"It's been a tremendous opening day and the action has lived up to the billing at this historic 40th Hong Kong Sevens," said World Rugby CEO, Brett Gosper.
"All of the 28 competing teams have impressed and the fans have been treated to some exceptional sevens, and it is only going to get better from here."
Uruguay, Russia, Papua New Guinea, Spain and Zimbabwe all maintained 100 percent records after the opening pool matches on day one of the Sevens World Series qualifiers.
Twelve regional qualifiers - two from each World Rugby region - are competing for a place as an ever-present team on next year's 2015/16 series with the winner of the qualifier replacing the bottom-ranked of the 15 current core teams at the end of the current series.
World Series Day One results:
Fiji 38-12 Samoa
New Zealand 26-7 Scotland
South Africa 24-0 Argentina
United States 21-14 Kenya
Canada 28-12 Belgium
Australia 33-5 Portugal
France 24-7 Japan
England 26-19 Wales
Source: @WorldRugby7s