What do you say if you're Michael Cheika right now?

Michael Cheika is confident Australia will close the gap to New Zealand for the second round of the Rugby Championship after a disastrous first 40 minutes in Sydney.

The Wallabies were outclassed early in the opening game on Saturday as the All Blacks ran in six tries to take a 40-6 lead at the break, Steve Hansen's side exposing massive flaws in Australia's defensive play.

A mix of pace and precision left the crowd at ANZ Stadium silent and a humiliating defeat looked on the cards, but Australia restored some dignity with a second-half fightback - the match finishing 54-34 to the world champions.

Cheika was highly critical of his side's performance in his post-match media conference, but is confident they can improve before the return clash in Dunedin next weekend.

"I think it was pretty plain to see that our defence was not good enough at all, the tackling's got to be better," he said.

"That first part of the game is not the level that you can be at, not in any game, let alone a game against them [New Zealand].

"With the team we've got, the points should be coming, we've got an attacking type of team so we should be scoring points, but you've got to have both sides of the game.

"We've spoken about it, everyone understands what we need to do to rectify it next week - both mentally and on the training paddock."

Our #Wallabies have fallen to the @AllBlacks in the #BledisloeCup opener. #AUSvNZL pic.twitter.com/5dezUk3cn2

— Qantas Wallabies (@qantaswallabies) August 19, 2017

He added: "But I know that we'll improve. We've got to do some quick improving before the next game because we want to keep this series [the Bledisloe Cup] alive.

"I don't think there is going to be a lot of changes, the change has to be more about believing in ourselves to make the hits when we need to, making sure we're coming up in defence and not worrying about what the opposition might be doing.

"They'll do it. This group have a very strong connection, this is a road block in front of course, it's going to knock us down but it's not going to stop us."

Captain Michael Hooper was equally deflated by the first-half display and called for more belief ahead of match two.

"It's not the start we would have hoped for in this series," he told Fox Sports. "I'm really proud we showed that Australian spirit to come back. Some guys in our team really stood up to the challenge."

In his post-match media conference, he added: "We've got to stick by the things that we've been doing, the things that we've been preparing for the last however long.

"It [second-half performance] showed that we did, we got some points on the board. It's the ability to do that from the start of the game is what we'll be looking to do next week."