And yet there is an air of optimism around the Wallabies going into this match - they have appeared relaxed and nicely focused. And all is not well in Camp All Blacks. Expectation is high, but good health is not, with Dan Carter gone and key forwards Richie McCaw and Kieran Read battling injury at just the wrong time.
The Wallaby players have happily promoted the All Blacks as the No 1-ranked team with all the pressure and expectations to deal with.
Deans has reshaped this Wallaby side, and made tough decisions along the way. Men who might still have been key figures under another boss, such as George Smith, Matt Giteau, Phil Waugh and Lote Tuqiri, have been cut loose. And in a moment that says everything about his decisiveness, Deans changed his captain - James Horwill for Rocky Elsom - just weeks out from the start of the tournament.
Opponents - or make that Henry supporters - loved to suggest that Deans would not cherish flair as much as an All Black coach should. Yet he has stuck by Quade Cooper, the most notorious risk-taker in the game.
At almost every opportunity, Deans has trusted youth over experience, while surely knowing that in rebuilding the Wallabies, he might struggle to get the timing right in having players in their prime for this tournament.
His record as Wallaby coach is not as good as his employers and the fans would have hoped, ruined by the might of the All Blacks and a couple of shock losses elsewhere. Like another previous All Black coaching prospect, the Welsh coach Warren Gatland, Deans has dared to win through by arriving in New Zealand with a team on the upswing, while the All Blacks remained wedded to their ageing stars.
Who will emerge triumphant may come down to the bounce of the ball at Eden Park, but there can be no doubt that on limited resources, Deans has laid the foundations for an encouraging Wallaby future. The win over South Africa in the quarter-finals was absolutely vital to fend off any opposition to his reign, justify his earlier-than-expected reappointment, and show that his policies and methods are working to a significant extent.
The win lifted Australian rugby's spirits, and against the odds. Under the cosh for much of the quarter-final in Wellington, Australia emerged as victors, leaving the South Africans to wing, and whinge, their way home.
In Sydney eight years ago, Deans was the All Blacks' assistant coach, as John Mitchell's side fell to a shock semifinal defeat against the Wallabies. Rubbing salt into the wounds, George Gregan famously told the repeat World Cup failures they would have to wait four more years.
Sunday will be a defining moment for Henry. After a long career, this will be the game he is most remembered for, the one that lets him sleep best at night, or causes the odd restless moment. On the All Black record, he deserves to win the crown, yet as New Zealanders know so well, that is not how World Cups play out.
Deans' overriding priority is to deliver a third World Cup for Australia and he has committed himself to the wider Aussie rugby cause. Deep down, he would also love nothing better than to deliver a message to the NZRU by winning the game that matters most against Henry, one that will take place in the most famous All Black fortress.
It would be the ultimate rugby retort, delivered in New Zealand rugby's backyard. Should he fail, a fresh Wallaby contract means time is on Deans' side, not that he will want to wait four more years.
