South Africa lost the seven-over contest with two balls to spare with 15 runs to preserve heading in the final over sent down by Wayne Parnell.
“You have to remember that Dale Steyn and Morne Morkel aren’t here,” Domingo said after the match.
“So it was a great opportunity for guys like Beuran Hendricks, in his first taste of international cricket, to feel what the pressure’s about.
“Parnell’s done it for us before and been successful, but it wasn’t to be tonight. It’s all part of the process.”
The match could have gone either way by that point after some tight overs from Kyle Abbott, JP Duminy and Parnell’s first six balls slightly blunted the Australian middle order following a blistering start by David Warner in pursuit of 81.
The opener clubbed 40 from just 16 deliveries, including 21 off the first over bowled by Lonwabo Tsotsobe.
Brad Hodge (21 off eight) finished things off with two sixes in the last over.
Earlier Quinton de Kock (41 off 20) and Faf du Plessis (27 off 13) shared an unbroken 74-run stand to give the South Africans a competitive total after losing the toss and being asked to bat first.
Domingo refused to blame Tsotsobe’s first over for the defeat, which put them 1-0 down in the series ahead of the final game at Centurion on Friday.
“That’s what David Warner can do to you. It’s just one of those things in a game of that nature.
“I think we had 11 after three overs and ended up getting 80, that means in the next four we got 69 or so and that’s going to happen in these short formats.
“It was a disappointing start and would have been nice if we gave away just eight. That would have put them under pressure, but it wasn’t meant to be.”
The match was in doubt in the build-up due to heavy rain through Wednesday afternoon in the east coast city, but eventually got underway two-and-a-half hours later than the 6pm scheduled start.
The first match in Port Elizabeth was also washed out.
Even though they lost, Domingo was not too disheartened.
“There’s always a lesson no matter how many overs you play.
“We’ve had a few in the last two years where we’ve had seven or eight overs reduced. Australia won the game and deserved to do so, but I wasn’t too disappointed about the way we played.”