South Africa Captain Gerrit-Jan van Velze said: "We certainly started off on a good note but we're aware that we conceded two tries in the last 20 minutes of the first half. We pride ourselves in defence so we must look at this before the Scotland game."
In contrast, Scotland conceded three tries in going down 29-17 to Samoa and realise that nothing other than a water-tight defensive wall will prevent the Springboks from running wild once again.
Coach Colin Robertson said: "The scoreboard didn't reflect the game, in fact I thought the two late tries distorted the final score. We had worked out a good game plan for Samoa and for most of the time we frustrated them and caused them problems. But just a couple of errors cost us the match.
"Once again it comes down to errors. We can't afford to make them otherwise we will pay for it. Still, it is the best we've played all season."
Providing Scotland don't beat the fancied Springboks, Samoa can cement their place in the 5th to 8th category by upending the USA.
Samoa Team Manager Sami Leota: "Friday night was excellent. It was a good effort from the boys and we got what we wanted. We coped well with Scotland's scrum and managed to hold our own. What made the difference was our running backline."
Tickets for all Junior World Championship match days are £2 for children and £8 for adults and are available at all match venues right up until kick-off.
Pool B (The Racecourse, Wrexham)
5.00pm Samoa U20 v USA U20
7.00pm South Africa U20 v Scotland U20