The government has faced repeated riots over its failure to provide proper homes for millions of people, nearly 16 years after the advent of democracy.
Now squatters are vowing to cause chaos as the global spotlight falls on the host nation when the month-long tournament kicks off in June.
Police could be forced to flood high-risk zones to protect foreign fans from demonstrations which commonly involve the throwing of stones and burning tyres.
The latest threats came on Tuesday in Mamelodi East, a sprawling area of shacks where thousands live without electricity or running water five miles from 2010 host city Pretoria.
Vusi Nkosi, one of the camp's 6,000 squatters, told South Africa's Beeld newspaper: "If the government could spend millions of rands and prepare for the World Cup so quickly, it's a disgrace that people are still living in squalor in squatter camps.
"The soccer means nothing to us because we won't be able to watch it anyway, since we don't have electricity."
Locals have also threatened to lash out in front of World Cup visitors with aggressive foot stamping and singing previously used by freedom fighters in the African National Congress party (ANC) before Nelson Mandela led them to victory in 1994.
Mr Nkosi added: "This time we will fight and toyi-toyi like the ANC taught us."
Mamelodi is around 40 miles from Soccer City, the World Cup flagship stadium in Johannesburg where the opening match and final will be played.
The government has budgeted £113m for security during the Fifa event, with millions also being channelled into new stadiums, roads, airports and tourist accommodation.
Shack dwellers who have endured more than a decade of democratic rule without decent housing are livid that their needs have been overshadowed by the football spectacular.
Riots have also recently erupted in townships surrounding Brits, a town near host city Rustenburg where England will play their first match against the USA.
At the scene of Tuesday's protests, Veronica Mphahlele, the Mamelodi community leader, hit out at the government for promising deprived families permanent homes and land of their own in 2000.
She said: "It's 10 years later and we're still in the same position. All they do is send police to come and shoot at us."
The Mamelodi protests prompted a nearby campus of the University of Pretoria to close its doors, students said.
Officers opened fire with rubber bullets, a routine form of control over protesters who blockade roads and force public buildings to close.
Kgaogelo Lekgoro, the provincial housing minister, reacted to the demonstration by repeating a government pledge that 5,000 houses would be built over the next three years.
Around 450,000 foreign fans are expected to travel to South Africa for the World Cup, 25,000 of them from England.