Eoin Morgan credited England's experience of holding their nerve in close games as a key factor behind their four-wicket win in Paarl.
For the second game in succession, England clinched a last-over victory after South Africa had appeared to be in the stronger position deep into the run-chase. It gives them an unassailable 2-0 lead in the three-match series.
But although it looked in both games as if England were falling behind their required run-rate, Morgan suggested there were deep reserves of confidence in the dressing room that enabled them to sustain belief even under pressure.
While England have rarely played anything like a full-strength T20 side since the 2016 T20 World Cup, they have enjoyed great success in 50-over cricket utilising a squad with the same nucleus of players. Over the last four or five years, they went to No. 1 in the ODI rankings before sealing their legacy "by the barest of margins" in the 50-over World Cup final.
At the same time, more of their players have gained experience in the top T20 leagues - there were 10 England-qualified players at this year's IPL - providing them with greater familiarity of the pressures that come with playing on the biggest stages.
"The experience helps," Morgan told Sky Sports. "Knowing how to win is one thing, but having that experience in our playing XI helps massively. Having been there before, we can hold our nerve.
"We weren't up with the run-rate but, with a long batting line-up and a short boundary, you're only one over or two maximums away [from catching up] the whole time. We have guys who can hit boundaries down the order."
Dawid Malan made a similar point. Malan claimed the player of the match award for his well-paced half-century in a relatively low-scoring match and afterwards expressed the view that England's experience in white-ball cricket should bode well for their T20 World Cup campaign in India next year.
"The core of the team has played together for the last five years," Malan said. "They won that World Cup, they have experience of playing white-ball cricket, they play in the IPL and other big tournaments. They're used to playing on the big stage and getting over the line. That's a great habit to have as a team.
"There are so many match-winners in that side. If you look at the batting line-up, everyone can win you a game."
On this occasion - as so often in his recent rise to the No,1 T20I ranking - it was Malan who won the contest, largely by keeping faith in his ability to catch up later in the innings after a tricky start to England's run-chase, particularly against the wristspinner Tabraiz Shamsi. With five overs remaining, he had made 25 from 30 balls but then turned up the tempo to crack 30 from his final 10.
"I found it really hard," Malan said. "Especially against the spinners. You're not used to them bowling that slowly in T20 cricket and, with a big boundary to one side and the wind, it wasn't really an option to take them on.
"But with the short boundary on one side, you back yourself to be able to catch up. You're always one over from catching up.
"The core of the team that played in the 50-over World Cup are well-versed in winning. If we can keep winning these tight games, it will put us in good stead ahead of the T20 World Cup."
The match also represented something of a happy homecoming for Malan. While he was born in Surrey, he was brought up and schooled in Paarl. He made his debut in first-class and List A cricket on this very ground in 2006 and his parents still live in the area.
"I made my first-class debut here," he said, "so it's nice to come home and win a game for England.
"Funnily enough, when I was fielding on one side of the ground, my high school coach was one of the guys throwing the ball back. And there was a guy the stands who helps me out by throwing me balls when I come back to South Africa and visit my parents. So there were two guys who have played quite a big role in my cricket at the ground in some capacity.
"It would have been fantastic to get a crowd in. And it would have been nice to have my parents here."
Both Morgan and Malan also praised England's bowlers who restricted South Africa to a total Morgan described as "a long way under par".
"Our bowlers set that game up for us," Malan said. "And because they set it up, we could take a bit of time."
"Everyone in the changing room will applaud the bowling unit which helped keep South Africa to a total that was a long way under par," Morgan said. "Everyone contributed and the wickets were shared around. The bowlers did an excellent job."
George Dobell is a senior correspondent at ESPNcricinfo