Cape Town - The Blitzboks have beaten a plucky Spain side and still can win the World Rugby Sevens title provided they win the Paris tournament.
After Fiji were sensationally beaten by England 19-17 in their quarter-final match-up, South Africa knew that a tournament victory in Paris would see them defend their series title.
But to their credit Spain, who they faced in the Cup quarter-finals, gave South Africa some trouble, forcing the match into extra-time after a score at the death tied the match at 10-10.
South Africa opened the scoring with an unconverted try by Dewald Human before Pol Pla crossed the whitewash for the Spanish to see the teams level 5-5 at half-time.
The Blitzboks struggled early in the second half, looking disjointed, but managed to score in the left-hand corner through Dylan Sage for a 10-5 lead with three minutes left.
But Spain were not done and after South Africa could not control a high kick the TMO was consulted.
Manuel Sainz-Trapaga was adjudged to have scored the try that levelled the match at 10-10.
With the conversion to come, Spain could have caused the upset of the tournament, but it flew wide of the uprights.
Extra-time saw more mistakes from the Blitzboks, but Justin Geduld got the crucial score and secured a 15-10 win to see the Blitzboks into the semi-finals where they will face old foes, New Zealand at 14:25 SA time, in a match they simply have to win.
Should they do so, they will face either England or Canada in the final.
Earlier, in a pulsating encounter England scored well after the final whistle to condemn Fiji to defeat, opening the door for South Africa.
England won 19-17 after trailing 12-7 at half-time.
They scored tries through Harry Glover, Dan Norton and Tom Mitchell with Mitchell and Dan Bibby adding conversions.
Fiji crossed the whitewash through Eroni Sau, Vatemo Ravouvou, Jerry Tuwai with Ravouvou adding a conversion.
The best place Fiji can now secure in the tournament is fifth.