The simple explanation is irrespective of how well you prepare, how great a team you have individually and collectively and how ready you are to rock and roll, there is an opposition and it is how they allow, or more importantly, don't allow you to play which is the critical and determining factor.
Perhaps the most crucial part of this battle will be at scrum time. New Zealand will be aware they can literally ensure victory if they gain a clear ascendancy here.
It has been Australia's most vulnerable area and the reverberation of being beaten up at scrum times spreads a long way through the team.
The Blacks will be seeking to dominate the loosehead contest and, as with the earlier match-up in Auckland this year, ripple the pressure through on the Wallaby 9 and 10 in Will Genia and Quade Cooper.
But I expect the Australians to have worked overtime on their combinations at scrum - not to mention the lineout - but coach Robbie Deans will await anxiously the outcome of the early exchanges to know if his team will compete and set a vital platform.
The breakdown will be a massive contest. The flank men have played a huge role thus far in the tournament, winning almost half of all man of the match awards.
My quick assessment on the key personnel in the ball fetching role is that in Ritchie McCaw, you have the game's outstanding captain.
But in David Pocock, the Wallabies have the most dynamic and best all-round No 7. But of course these two great warriors won't thrive in isolation.
So to the inside backs and first use of possession.
The battle of the halfbacks will be absorbing. Piri Weepu needs to have another big match for many reasons. He has to nurture the inexperienced Aaron Cruden alongside him but the Wellington brotherhood around Cruden will no doubt ease pressure. Weepu has to be both calm but very busy but thus far he has thrived in the structured and disciplined environment of the All Black squad.
Genia is a big match player and could easily be the man on which the game turns as we saw in Brisbane at both Super Rugby and Bledisloe level this year. No doubt the New Zealand back row will look to aid Cruden in defence and this could present Genia with the crucial gaps his sniping can exploit.
The injury loss of Dan Carter cannot be underestimated.
His strength was that he could execute at the area of contact many attacking options, leaving defenders constantly guessing. He attracts defence and therefore leaves space elsewhere for support players.
In such a crunch game, young Cruden will likely just play a link role. He could execute this role well but he should be predictable. It should allow for the Wallaby defence to focus on the other danger men in black.
Then the million dollar question. Which Quade Cooper will turn up tonight? I predict he will turn up with his A game and, if so, that could well be game, set and match for the Kiwi party.
* PS: My heart went out to the Welsh last night. They were the best and deserved their day in the sun on Sunday.
Let's wake up and do what our league mates do - put players on report and not jump to game-ruining, stupid conclusions.
The Welsh did not deserve to have their dream destroyed by a knee-jerk reaction.
