All Blacks primed for Wallaby showdown
The winner will be the first team to win the World Cup three times, and if it is reigning champions New Zealand they will be the first team to successfully defend the title.
Australia know if the All Blacks are below par one week they bounce back with a vengeance the next. Hansen said they were below par when scraping into the finals with a 20-18 win over South Africa on Saturday.
Australia beat Argentina 25-19 in their Twickenham semifinal on Sunday.
Wallabies coach Michael Cheika believed his side would be better next week while Hansen was certain the All Blacks would improve.
"We could have done better [against South Africa], and we always seem to play better when we're like that," the New Zealand coach said.
Hansen did not have to go too far back to underscore his point.
When the Wallabies beat the All Blacks 27-19 in August, New Zealand bounced back with a 41-13 victory a week later. Last year, a 12-12 draw in Sydney was followed by a thumping 51-20 victory for the All Blacks. Australia beat the All Blacks 25-20 in the lead up to the last World Cup only for the All Blacks to win their semifinal 20-6.
"If you go back four years ago, we had a sensational performance against Australia in the semi and then really didn't lift the next week even though it was a final," Hansen said referring to the 8-7 World Cup final win over France.
"So coming off what was a good performance but wasn't a great one I think we'll lift. There'll be enough excitement in the back of our minds knowing we could have done better."
But while Hansen was not overly pleased with the way the All Blacks beat South Africa he said it was the right preparation for a final against Australia as it highlighted areas his side needed to address.
"A really tight, tough game where we probably didn't play as well as we could have, and the opposition had something to do with that, but some of our own stuff needs to be looked at. 
"So we'll go into this game on the weekend really hungry for a performance and it won't be over-rating ourselves which is good."
Hansen did have an issue with the high number of penalties conceded by the All Blacks and with some refereeing decisions, saying he would raise this with World Rugby's referees boss Joel Jutge.
Hansen said a review of the South Africa match tape left him puzzled by some calls by French referee Jerome Garces.
"I have watched it and a lot of the penalties were justified. There's a couple of them I don't agree with so I'll have to talk to Joel about the interpretation.
"The only concern I've got is whilst we are being penalised for things the same things are happening on the opposition and they weren't so that will be something else I'll talk to him about. You just want consistency."
Agence France-Presse
