A World Cup winner as a player, assistant coach Nathan Grey plans to sharpen the knife of the Wallabies’ defence heading into this month’s tournament.

Grey was part of the triumphant 1999 squad along with fellow assistant coach Stephen Larkham and both were also in the 2003 squad who finished runners-up.

Former centre Grey is charged with the responsibility of organising the defensive line of the 2015 side who begin their campaign in two weeks against Fiji in Cardiff.

Grey likes what he’s seen of the Wallabies’ defence so far this year.

Asked if he was happy with it through the five-Test program, Grey told AAP “I am.

“It’s a continued work in progress. You need to be looking at how you can sharpen the knife and how you can continually improve your defensive performance and it’s something that we are always working on.

“We need to be better, we need to be more consistent and we’re training accordingly.”

The defending world champion All Blacks proved Grey and his charges still had work to do after they breached the Wallabies’ line five times in the second Bledisloe Cup clash of the season in Auckland.

“That game just highlights how important that, in the upper echelon of rugby circles, that you get crucified for little mistakes,” Grey said.”

“One missed tackle here or there and that’s a try. Very good teams make you pay for defensive errors.

“You need to be very, very well equipped to deal with structured defensive situations, but also unstructured situations where you need to scramble and you need to survive and defend your line with a lot of passion.”

It was his passion for defence that helped Grey earn 35 Test caps.

“I wasn’t blessed with an awful lot of talent so I had to ensure that my contribution to the team was from a defensive side of the coin and from a physical side of the game,” Grey said.