FIFA release 5,000 knockout stage tickets
The tickets had been reserved by fans hoping Bafana Bafana and Group A favourites France would reach the last 16.
Instead, Uruguay and Mexico qualified from the section and will face South Korea and Argentina respectively.
"We have some of the reserved tickets coming back for public sale," FIFA spokesman Pekka Odriozola said on Wednesday.
"These tickets are coming back from teams that were eliminated such as France and South Africa."
There are 4,000 tickets available for Saturday's Uruguay-South Korea match at Nelson Mandela Bay stadium in Port Elizabeth and 1,000 for Sunday's Argentina-Mexico clash at Johannesburg's Soccer City.
FIFA had been criticised for its early online ticketing strategy that excluded many poor South Africans but later it opened cash ticketing offices which witnessed long queues.
Football's world governing body said 97 percent of tickets had been sold for the finals despite empty seats at the stadiums.