Australia scraped through their opening encounter after an outstanding bowling performance and some critical cameos with the bat from Steven Smith, Marcus Stoinis and Matthew Wade.
They made a bold decision to leave out both Agar and Richardson, who had been automatic selections for most of the last two years in a five-man attack, with Agar currently the highest-ranked Australian at No. 6 on the ICC T20I bowling rankings.
But Australia opted for four specialist bowlers only with Glenn Maxwell as the fifth bowler. Mitchell Starc, Josh Hazlewood and Pat Cummins played together for the first time in a T20I despite the slow nature of the Abu Dhabi surface, with the plan working to perfection.
"It was a very, very difficult selection," Langer said. "But because we went for the 7-4 set-up rather than the 6-5, and we felt that we were very well planned against South Africa, we knew that we wanted to try and make an impact in the powerplay overs, in the first six overs, we've seen that through the IPL. And we also knew the strength of South Africa upfront so, and thankfully it worked yesterday.
"I can't emphasise enough how tough it was on Ashton Agar, his numbers are literally outstanding. Tough on Ash and really tough on Kane Richardson who's probably, arguably our best death bowler, or a very good bowler in these conditions so it's nice to have those selection headaches."
Langer said the players are well aware that team selection will be dictated by the conditions as they had done in the 50-over World Cup in England in 2019.
"We've said from day one to the players and we did it in the last World Cup, we did it to a degree in the last Ashes in England, that we'll just look at the conditions, we'll look at the opposition, we'll look at the match-ups, and we'll make the call that we think is right for the team," Langer said. "It doesn't always work out that way, but with all the information we've got, we'll work through that."
One area where Australia are unlikely to make any changes is their opening partnership despite both Aaron Finch and David Warner struggling for form and runs. Both missed out against South Africa but Langer was confident his two most experienced openers would come good sooner rather than later.
"There's some really good signs from Davey yesterday," Langer said. "I think he pulled Rabada for four, he played a beautiful cover drive, he played a great cut shot, and then one held up on him a bit. But they're good signs for me.
"He's in as good physical shape as I've ever seen him so that's a very positive sign, [I'm] really confident he'll come good.
"And Finchy, I thought one, Finchy's captaincy was brilliant yesterday. And he's another one that, he had knee surgery, it might take a little bit of time for him to get moving. He's working hard in the nets in his preparation. I don't think it's so much a mental thing for Finchy. I think it's just getting back into some rhythm, getting used to his leg feeling good again.
"They have been and are a world-class opening partnership and I honestly believe when those two get going, that's going to set us up for real success in this tournament."
Langer admitted he had nearly chewed his fingernails down to the quick in Saturday's last-over thriller. But he expects more close low-scoring games as the tournament moves on.
"We're going to have to get ready for it, there's going to be some very, very close games I think," Langer said. "It's usually what happens on these sorts of wickets.
"We go to Dubai today; our next game is in Dubai. West Indies were bowled out for 55
I think yesterday in those conditions. We'll work it out and hopefully we'll get it right more often than not."
Australia face Sri Lanka in Dubai on Thursday.
Alex Malcolm is an Associate Editor at ESPNcricinfo