But they advanced to the quarterfinals for a 10th time in 10 outings this season despite a loss against the USA in their final Pool match.
Defeat meant that the USA topped Pool A, leaving the Blitzboks to face hosts England in the last eight.
England have been a bogey side for SA this year, beating them three times, including in the final of the Cape Town leg of the series.
It’s a chance for SA to return to the favour in London on Sunday.
The Blitzboks eked out another narrow win beating Wales 12-10 in game two, which was enough to seal their semi-final place even before their final Pool match against the USA.
America surprised the Blitzboks with their second resounding performance of the day, having earlier beaten Kenya 47-0.
They ran into a 12-0 lead over SA before tries from Ruhan Nel and Siviwe Soyizwapi drew the scores level early in the second half.
But the USA lifted the tempo and the Blitzboks could stay with them, conceding a further two tries as they went down 24-12.
Craig Ray – Tiso Black Star Group/Tiso Black Star Group Sport