The Springbok Sevens will now play Scotland, the second qualifier in Pool B, in one of four Cup quarterfinal encounters early on Sunday morning (04h42 SA time).
A strong comeback in the second half, which resulted in three quick tries, enabled the South Africans to defeat a much improved USA 24-15 in a lively rugby match. The win saw them complete their group fixtures unbeaten and on top of their pool.
Speed merchant Carlin Isles opened the scoring for the USA but the SA skipper Kyle Brown levelled matters quickly when he crashed over in the corner. Another USA try by Durutalo saw them going into the break with a 10-5 advantage.
However, three tries in quick succession by Cecil Afrika, Werner Kok and Ruhan Nel gave South Africa much needed breathing space before Danny Barrett pulled another one back for the USA to bring the match to and end at 24-15.
South Africa kicked off their campaign by outplaying Canada 29-7, with wing Seabelo Senatla helping himself to another hat-trick of tries. Kwagga Smith and Werner Kok, the top tackler this season and also a prolific try scorer, added two more tries to the SA tally.
In the battle of the two African rivals, Kenya gave the South Africans a tough battle especially in the first half. Justin Geduld dotted down for the only try of the opening half. The Springbok Sevens took the initiative in the second half and completed a fine performance by adding three more tries through Smith, Chris Dry and Rosko Specman for a comfortable 26-0 win.
With one day remaining in Tokyo and just two more tournaments to come after the Japanese event, South Africa (110 points) currently have a slender two-point lead over Fiji, with New Zealand three points back. The top four teams on the final World Series standings at the end of the season in May will qualify automatically for the 2016 Olympic Games in Rio.
All matches are shown live on SuperSport 6 and rugby fans can also follow the progress of the Springbok Sevens at the tournament on Twitter at @Blitzboks.
The Cup quarterfinal draw for the Tokyo Sevens on Sunday:
Fiji vs Japan
South Africa vs Scotland
France vs England
New Zealand vs Canada
Original source: Blitzbokke face Scotland in quarters