Cape Town - The Blitzboks got their Singapore Sevens title aspirations off to the perfect start, trouncing Japan on Saturday.
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The Blitzboks ran in eight tries to win 52-0, having led 21-0 at half-time.
Siviwe Soyizwapi completed his hat-trick while Zain Davids scored his debut try.
Later on Saturday, the Blitzboks face France (09:06 SA time) and England (13:02).
France earlier beat England 24-14 in the first game in Pool B.
South Africa, 23 points ahead of Fiji in the 2016/17 World Rugby Sevens Series standings, have won four of the seven tournaments so far this season.
Tries: Werner Kok (2), Siviwe Soyizwapi (3), Dylan Sage, Zain Davids, Sandile Ngcobo
Conversions: Branco du Preez (5), Ruhan Nel