The Springbok Sevens side scored 19 unanswered points as they surged into the Cape Town Sevens final, surviving a scare to beat Spain 19-12 in their semifinal.
The Blitzboks will now face France in the final at 7.11pm. France beat Fiji 19-17 in their semifinal.
But it was anything but easy going for the home side as they put in a poor first half, missing tackles and looking out of sorts as the Spanish dominated.
Spain continue to be the find of the HSBC SVNS series thus far and added Kenya and Australia on Saturday to their two wins against the All Blacks in Dubai to underline the danger they pose.
And in that first half after several forays into the Blitzboks 22 metre area it was Eduardo Lopez who finally crossed the line for a well-deserved try.
Alejandro Laforga split the defence 90 seconds later to put them 12-0 up with the Blitzboks uncharacteristically missing several tackles in the lead up yo the try.
It was only when a turnover was spread wide and captain Impi Visser got into space that the home side started to look dangerous.
Visser had a one-two with Quewin Northe before his inside pass for Zain Davids missed the hands and landed on his foot, being kicked forward in the process with Davids pouncing for the try.
The Blitzboks quickly hauled in the seven point halftime deficit early in the second half when Shilton van Wyk was put into space and a brutal left step opened up the portal to the tryline.
Tristan Leyds then took them ahead with a show and go that flummoxed the defence before Shaun Williams had a try disallowed in the corner when his foot hit the touchline.
The Blitzboks held on for their first final in four years at their home tournament and now have a chance to win their first title in Cape Town since 2015 in the final.