The All Blacks were also upset by the Wallabies in the final season of the Tri-Nations four years ago but put the Brisbane defeat behind them and steam-rollered Australia in the semi-finals on the way to a second World Cup triumph.
"We just got beaten by a better side on the night," said Hansen, who has only tasted defeat three times as All Blacks coach.
"We have to face up to that reality. It's an inconvenient fact. But we've been here before, we've lost games before and doesn't mean to say we've become a bad side.
I would prefer to have no off nights but I think in 2011 we had an off night in Brisbane and was something we learnt from and we have to learn from this one. You bottle up the hurt and you make it work for you.
Both Hansen and Richie McCaw were bemused as to how the often derided Wallabies scrum managed to cause the All Blacks problems all evening but the captain was more concerned at two fluffed kickoffs and a string of missed tackles.
"They're inexcusable those sort of errors to be honest," said the 34-year-old, who was on the losing side for just the 15th time in his record-equalliing 141st test.
"You want to start well and when you do that, you're under the hammer straight away. It's a bit disappointing the errors we did make. We've got to make sure that we turn that around. We're going to have to."
One positive out of a disappointing evening for Hansen was the performance of outside back Nehe Milner-Skudder, who scored two tries on debut.
Australia, Rugby Championship 2015
Image credit: AFP
"He's exciting. He's confident and he's impressed us with how quickly he's taken things on board," Hansen said.
"The first one he didn't have to do too much apart from catch the ball and run, but the second one he had a bit of work to do and showed pretty good effort to score it."
The All Blacks have an opportunity to reassert their dominance over the neighbours at their Eden Park fortress in Auckland next week -- a match they must now win to avoid relinquishing the Bledisloe Cup after holding it since 2003.
"I guess we're a bit lucky we get another crack at it next week," said flanker McCaw.
"I know the boys are hurting and if that's going to bring the best out of them, then next week will. But just because you play at Eden Park, doesn't mean it's going to happen automatically."