Wales, thoroughly outgunned in the scrum and clueless in attack, were fighting a losing battle from the off.
It was their biggest defeat by the Boks since a second-string Wales side went down 96-13 in Pretoria in 1998.
“It was good, we’re proud of today and the whole tour,” South African captain Siya Kolisi told S4C.
“We’ve been building depth into the squad. We respected Wales as much as we could, and we needed to go out and play our game.”
Wales skipper Dewi Lake acknowledged his team had been “overpowered”.
“We can’t ignore the score and the performance,” he said. “When you play the best team in the world, you need to step up and we didn’t have any ball to play and that cost us.”
Feinberg-Mngomezulu scored two tries and nine conversions for a personal tally of 28 points that took him to 123 points in 10 matches for the green and gold in 2025.
Centre Andre Esterhuizen was another star. His barnstorming midfield drives were a constant thorn in the Welsh defence and offered South Africa relentless momentum.
The Welsh scrum was under the cosh from the vaunted Bok pack and the opening three tries, from Gerhard Steenkamp, Ethan Hooker and Jasper Wiese, all came from dominant attacking set-pieces.
One rare Welsh foray into the Bok 22m area saw an overthrown line-out and subsequent penalty for South Africa in front of 50,112 in the Principality Stadium.
An Esterhuizen crash ball set up a ruck from which scrum-half Morne van den Berg darted over for South Africa’s fourth try, with Feinberg-Mngomezulu impeccable from the kicking tee to leave them 28-0 up at halftime.
Wales had a terrible start to the second period, with No 8 Aaron Wainwright going to the blood bin before another Esterhuizen drive set up a ruck from which Wilco Louw barged over.
Welsh woes were compounded by Taine Plumtree’s yellow card.
“I smell Welsh lamb on the braii!” one South African fan had written on her cardboard placard. So it proved as the floodgates opened.
Feinberg-Mngomezulu, who as a teenager spent a year at Llandovery College, Carmarthenshire, on a rugby exchange from his Cape Town school, took a quick tap penalty to surge under the posts for South Africa’s sixth try.
Canan Moodie then latched on to a loose Dan Edwards pass to hack ahead and touch down, before Esterhuizen finished off a sweeping move down the left for a deserved try.
South Africa coach Rassie Erasmus, known for his innovative approach, brought on all eight replacements, including 140-cap lock Eben Etzebeth, in the 52nd minute.
While the game lost some of its rhythm, South Africa gradually settled and Feinberg-Mngomezulu skipped in for his second try before Ruan Nortje. Etzebeth also went over to leave Wales coach Steve Tandy with a mountain to climb before their Six Nations opener away to England.
Etzebeth blotted his copybook, leaving after French referee Luc Ramos had no option but to red card the Bok enforcer with just minutes to play for an eye gouge on Alex Mann.
