Some 700,000 tickets for the first World Cup hosted in Africa are available for purchase out of a total of just over 3 million for the 64 games between June 11-July 11 next year.
Fans have until the end of March to apply for tickets before going into a random draw lottery in April to determine the successful applicants.
"The beginning of this part of the build-up to the World Cup is our irrevocable promise that we make to the people of the world that all is in place and will be ready for 2010," said Organising Committee chief executive officer Danny Jordaan.
The readiness of South Africa's stadiums and infrastructure has come under scrutiny but FIFA President Sepp Blatter said in December there was "no plan B".
Immediate figures were not available from FIFA or the Organising Committee for the first hours of Friday's sales but Jordaan said he had been told the response had been good.
"We have had people queuing up at the banks to get application forms. We are very happy with the response we have had, it seems there is huge interest."
"We kindly ask fans for patience and would like to remind them that the first ticket sales is not conducted on a first come, first serve basis," it said.
"All the applicants who correctly apply for tickets between 20 February and 31 March 2009 will have an equal opportunity of obtaining the tickets for which they have applied."
