Two tries from Gavin Henson and an injury-time score from Dwayne Peel capped a remarkable fight-back that saw Wales come within two points of the reigning Tri Nations champions.
And the Newport Gwent Dragons outside, who helped spark the late comeback after replacing the injured Shane Williams, believes that performance has given Wales heart before facing Romania this Friday and New Zealand eight days later.
'South Africa were probably the most physically strong team we have ever played but they didn't bully us the way they perhaps did out there in the summer,' said Sweeney. 'The fact that we finished stronger is testimony to the fitness work we have been doing but the annoying thing was that there tries came from our mistakes.
'We spilled the ball a few times and they were clinical. We need to be more like that.
'It was good to get on against South Africa, thankfully I didn't have to go on the wing, and I'm fairly pleased with how things went though obviously I'm desperate to start on Friday.'