Justin Marshall: The All Blacks' tough tactical decision

The runs and offloads of Sonny Bill Williams could be crucial for the All Blacks' success tomorrow night. Photo / Getty

You can't boil down a Bledisloe Cup test into a single tactic but what the All Blacks choose to do with the Wallabies inside defensive channel could have a massive bearing on the result.

That channel, which will be manned by Nick Phipps, Bernard Foley and Matt Giteau will be shining like a giant neon "This Way" arrow for the All Blacks, especially with Sonny Bill Williams starting at second five-eighth.

Phipps, Foley and Giteau are all courageous defenders and they'll make their tackles, but that's all they'll be able to do. They're not aggressive defenders. They just don't have the strength or height to make dominant tackles against the likes of SBW.

Expect also to see debutant Nehe Milner-Skudder come into first receiver to give them grief. As has been discussed in a previous column, Milner-Skudder is bigger and stronger than he often gets credit for and he can also find weak shoulders with his lightning footwork. he, as well as SBW, is a genuine offloading option.

With SBW, they won't be able to tackle him from the hips up. Their only option, if they're in a one-one-one situation, is the hips down and bring him to ground immediately, before that mitt extends and he throws another offload.

So this channel will be incredibly tempting for the All Blacks to continue to exploit.

But, and this is a big but, this might be a double-edged sword. There could even be an element of the Wallabies luring the All Blacks into a trap. If these guys make their tackles, and I expect they will, then lurking near that inside channel will be Michael Hooper, David Pocock and Scott Fardy. In reality, Hooper and Pocock are likely to be numbers one and two to that tackle area. once there, unless they are forced to travel backwards or laterally to the ruck, they will at best disrupt the All Blacks ball, at worst turn it over. Instead of the inside channel being the quickest route to success, it suddenly looks like a danger zone.

There's two ways of looking at what the All Blacks should do if they are disrupted by Australia's twin opensides.

One, they keep plugging away, knowing that they are at least engaging the Wallabies two most effective forwards and eventually they will tire.

From my perspective, this is the least preferred option. This is a Wallaby team that seems to be growing in self-belief daily. If that self-belief is allowed to grow in-game, then they could quickly become a very dangerous beast. If I was in the All Blacks leadership group, I wouldn't count on Pocock and Hooper bending and wilting.

Two, they adjust their tactics on the hoof and start seeking out wider channels. I would be a proponent of this. It is fair enough testing those defenders early, but if it allows Hooper and Pocock to start gaining traction, I would change quickly and certainly not wait until halftime or beyond.

Those wider channels might not be such an obvious defensive weakness of the Wallabies, but the All Blacks, especially with the way they use their tight five as ball-carriers, are still good enough to cause problems out there.

For me, this could be a test of All Blacks leadership as much as ability. There's plenty of leaders out on the park, from Richie McCaw to Kieran Read to Jerome Kaino and the Smiths, Conrad and Ben. They might need to make some tough tactical calls in what is shaping as an important test.