Andy Farrell hailed his team's resilience as Ireland came up trumps against the world champions in Paris last night.
The Six Nations champions withstood a second-half onslaught from South Africa to record a 13-8 victory and set themselves up for a chance to win Pool B when they take on Scotland in two weeks' time.
Under the cosh for long spells in the second period, Ireland survived four missed kicks to prevail by five.
"Our resilience which has been really good of late anyway, as you can imagine," Farrell told RTÉ Sport when asked what pleased him most about the win, their third in a row against South Africa.
"That was a proper game, a traditional game that had everything, there were ebbs and flows, ups and downs and how we managed to stay on point, mentally, was fantastic.
"The game was never going to be perfect. The first half I thought we had the rub of the green.
"As far as field position, we probably didn't captialise on that a little bit. But it was certainly roles reversed in the second half.
"But how we kept our heads, getting a couple of penalties at the end, when it really mattered is the big plus side of our performance."
As well as the 11 points that kickers Mannie Libbock and Faf de Klerk left on the field, Ireland overcame a malfunctioning lineout with six throws missing their targets.
It threatened to cost Ireland dearly but they somehow found a way out.
"Our discipline in the second half was very good. In the lineout it was roles reversed in terms of penalties, the early engagement. And the penalty that we got on their line to kick the [last] goal.
"Again, we stayed at it mentally and rolled with the punches but came out strong the other side as well."
So much was written in advance about the impact of the Boks' bench, which contained seven forwards.
However, the eight Irish replacements outshone the 'bomb squad'.
"Like we knew they would," said the head coach when asked about the how well his bench played.
"They don't just come on to the field and try to fit in they come on the field and try to add to our performance.
"The energy that they gave was absolutely fantastic and we knew they would 'cos that is how they train and that's how they compete for each other."
He also admitted that while the game could have gone either way, it was "huge" that they fell over the line first, given how deflating a defeat would seem, especially with a two-week lay-off.
"Let's be honest, it's wonderful to win. But there's not much in it between two good sides.
The best thing about it for us is we get to feel the intensity of a big game within this World Cup and know what it feels like for further down the line.
"How we are able to be a little bit more composed and accurate, and play our game a little bit more, is invaluable to learn lessons from the win.
"When you love defending as much as we did within that game, it stands us in good stead as far as our want and our fight for rest of the competition."
