That was the Springboks' third Tri-Nations defeat on the spin and prompted a week of criticism for the 51-year-old who took over from Jake White at the start of the year.
The most vocal critic was Saracens coach Eddie Jones, who was an assistant to White when the Springboks won the World Cup last year, who described De Villiers' tactics during the current Tri-Nations as "nonsense".
However, with the vindication of having just led his side to their biggest-ever win over the Wallabies, De Villiers took the opportunity to fire back at his detractors.
"My message to our critics will be that we hope they now unite behind us and support this team," he said.
"We hope they can stop stomping on the same players that brought them such joy just a few months ago in France and get behind them."
In a veiled swipe at Jones he continued: "They don't need to look abroad to find answers when it is right here in front of them.
"We know what we are doing. The players believe in the game plan and they can take this further. We are about 60 to 70% where we want to be on today's performance and we can get better.
"The players will take the wrong decisions in the future and they will make the wrong calls, but we will back them in this."
Springboks captain Victor Matfield said he was glad to have repaid the faith that De Villiers and his staff had put in the players after the coach resisted the temptation to make wholesale changes.
"I'm just happy that after we didn't do our jobs on the field in the last two weeks the coach and selectors resisted the call to sack us," he said.
"The faith they put in us was repaid and if we play like this, and get the momentum we got today, it gives me hope for the future."
Australia coach Robbie Deans was unperturbed at the loss.
His indifference can be traced to the fact the match was effectively a dead rubber for the Australians who can still claim the Tri-Nations for the first time since 2001 when they host New Zealand in a fortnight's time.
"I don't know how to feel about it really," Deans said afterwards.
"I don't know that I'm bothered with the stats. They got into the game early and got the momentum and we dropped off it and paid the price. That's what happens at this level.
"A Test loss is a Test loss and I am not concerned about the numbers. It hurts when you lose and we don't want to chase statistics. The fact is, it was a belting today (Saturday)."
He added: "The Boks are world champions and in this competition with the three best sides in the world, someone has to be on the bottom.
"These are good sides and if a side is on the bottom, it doesn't mean that they are not a good side. Someone has to be on the bottom and it takes little to go from enjoying a win last weekend to not enjoying it this weekend."
Despite the defeat the Wallabies claimed the Mandela Challenge trophy following their two previous wins against the Springboks in the tournament.
And while Deans was content to have delivered his first piece of silverware since taking over as boss, he felt more inclined to defend his fellow tactician De Villiers.
"There have been people feeding on Peter de Villiers for a number of weeks now and he is due credit," he said.
"That's how close it is from week to week. It can be one man or one team that makes the difference, and that is the reality of this industry.
"The only good feature is that it showed how much it took to lift that piece of silverware up there, and we now have the opportunity to achieve more."