The South Africans comfortably beat Japan 33-0 and Scotland 41-0 on Saturday after their 31-0 romp past hosts Russia on Friday to finish top of Pool B with a 105 points differential, the best in the competition.
The 17 tries scored by the Springbok Sevens team in their three matches was also more than any other team and they were the only outfit not to concede a try.
Coach Paul Treu heaped praise on the national side for their performance, but warned that everything would start all over on Sunday.
"The players know tomorrow will be the most important day of the tournament and will leave nothing out there," Treu said.
"We have been very impressive on attack and the way we defended resulted in our tryline hardly being under threat.
"We will be tested on Sunday and then we need to respond like this again."
Treu was confident of their chances against Fiji in the cup playoffs.
"This is a World Cup and if you want to be the best you have to beat the best," he said.
"They're a great sevens nation and are known as one of the best teams in the world but there is no better time for us to put them away."
Springbok Sevens captain Kyle Brown was cited for alleged eye-gouging following the match against Scotland, the SA Rugby Union confirmed, and he would appear before a judiciary on Saturday night.
Meanwhile, the SA
women's team finished third in Pool B, earning a 19-7 win over China but
falling to Ireland and Australia. They will face Fiji in the bowl
quarter-finals on Sunday.