Ex-president Nelson Mandela has said the award of the 2010 World Cup would be an ideal present for South Africa celebrating 10 years of democracy.
Mr Mandela is fully behind South Africa's bid
Mr Mandela told key backers that the tournament was worth $400m to the economy and would create 150,000 jobs.
He will join President Thabo Mbeki, Nobel prize winner Desmond Tutu and former president FW de Klerk in Zurich for Saturday's announcement.
South Africa is competing against Morocco, Egypt, Tunisia and Libya.
Fifa president Sepp Blatter has promised that the 2010 World Cup will be held in Africa for the first time.
A Fifa evaluation report to the five nations established the South Africans as favourites ahead of Egypt and Morocco, describing their bid as "excellent".
"In this year of celebration there could be few better gifts to us in our 10th year of democracy than to be awarded the 2010 world soccer cup," Mr Mandela told ministers, businessmen and leading sports officials attending a farewell dinner for the bid committee.
South Africa's lost their attempt to host the last World Cup by one vote when Fifa's Oceania delegate Charles Dempsey abstained, handing the 2006 tournament to Germany.
But the bid committee, spearheaded by Danny Jordaan, has left little to chance this time.
Jordaan has used all South Africa's big guns in his efforts
Oscar-winning actress Charlize Theron has still to confirm if she will join the high-profile delegation in Switzerland.
South Africa's bid campaign has spent millions of dollars on events and travel over the last 12 months lobbying the 24-member Fifa executive committee to vote for the country.
Archbishop Tutu has jokingly promised Fifa executive committee members "a free ticket to heaven" if they vote for South Africa.
The bid committee have worked hard to allay fears over the country's high crime rate.