OPINION: It's hard not to over-emphasise the loss of Conrad Smith as the All Blacks get set to open the crunch part of their test year with Saturday night's Bledisloe Cup battle against the Wallabies in Sydney.

The patience the All Blacks management have employed in trying to get Sonny Bill Williams cleared to be involved in this game and the rematch in Auckland a week later is perhaps more testimony to Smith's abilities than those of Williams with his unique skills.

Steve Hansen and the selectors have faced a conundrum trying to replace Smith.

Based on form, Williams is more than worth his place in the midfield mix though he's not the long-term solution with his impending departure to Japan. And as a short-term exercise it also presents some problems.

I'm not convinced Ma'a Nonu is a test 13 if that is part of the immediate solution. And the alternatives bring a touch of greenness to the midfield for an occasion as big as this in the form of Tamati Ellison or Ben Smith.

So there's plenty to ponder for the All Blacks and, again, that's because of Smith's commanding presence that we have all become so comfortable with in recent seasons.

I'd rate Smith the best centre in the world over the past year or so.

He was central to the World Cup success and he carried that form into the Super Rugby season, where his leadership qualities and playing skills were massive components in the revitalisation of the Hurricanes.

He has become a crucial part of the All Blacks machine, particularly with the retirement of some experienced personnel. Smith runs the backline defence out wide, his vision and passing game are second to none and he's such a sensible sort of guy that he just gels everyone and everything around him.

Don't get me wrong, his absence is not catastrophic because the All Blacks will always back their depth and that's the great thing about our game. But it is a concern and will certainly be a big talking point in the leadup to this fascinating match.

Offsetting the loss of Smith are similar problems for Australia. It's fair to say that since the great Stirling Mortlock slipped off the scene, the Wallabies have struggled with their midfield and their consistency of performance has suffered. Robbie Deans has tried a number of combinations without finding the right solution.

Good Wallabies teams pride themselves on their back play and their great sides have been blessed with superb midfield players like Mortlock, Jason Little, Tim Horan, Andrew Slack and Daniel Herbert.

The side are going to miss the injured Pat McCabe and James O'Connor, so that evens the playing field in this midfield area on Saturday.

This is the pivotal match in the Bledisloe Cup series. If the Wallabies are to have any chance of ending their 10-year drought they have to strike in Sydney.

Can they do that? By all accounts Deans and his team are under a ton of pressure to produce something special in this series.

They were less than impressive in their June efforts, scraping home in all three tests against Wales. Those performances won't have done too much for the Australian confidence. Nor will their efforts in Super Rugby.

Collectively though, they still present a formidable side as the Wallabies. They will also be fresh for action and have had the bonus of a month's training to work on their game.

The All Blacks looked very good at times against Ireland. It was a good transitional series for the new coaching team who also took the opportunity to blood some promising young talent.

But this is a very different prospect and will be the real test of Hansen's systems. With the Springboks and the Pumas bringing their own attributes, the Rugby Championship is a fascinating prospect.

We're lucky to have the Bledisloe Cup played out as a sub-plot to that. Outside of the World Cup it's the trophy that New Zealanders treasure most and that's why this week is going to be so interesting.

- © Fairfax NZ News