England, competing in Pool B, were pitted against unfancied China and ran in nine tries in a 59-5 triumph.
Mat Turner and Dan Norton scored braces, while Greg Barden ran in a hat-trick, but the loudest cheers were reserved for Wang Chongyi who scored China's sole try.
New Zealand were equally destructive against Korea, racing to a 61-0 win in Pool A.
Rugby
South Africa triumph in Vegas Sevens
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South Africa found themselves 5-0 down against Spain for almost five minutes in the first half before turning the match on its head with 33 unanswered points, while Wales joined them on one win in Pool E after defeating the hosts 35-12.
Pacific Island sides Fiji and Samoa, tied for third in the championship, also began with straightforward games - Fiji troucing Malaysia 59-0 and Samoa handing a tough lesson to tournament debutants Mexico, winning 64-0.
Scotland broke Tongan hearts with a late show and a converted try courtesy of Michael Fedo and Andrew Skeen to win 12-10.
Australia started the tournament with a 42-0 victory over Zimbabwe in Pool F, while Canada pulled off a famous 22-21 win against Argentina.
The group stage concludes on Saturday before the knockout begins on Sunday.
IRB Sevens
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IRB Sevens
England off to flyer in Hong Kong
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