KEY POINTS:
One team coming off World Cup glory and two with points to prove after freezing on rugby's grandest stage - this a Tri-Nations truly worthy of the name.
Pressure is mounting from all directions on an All Blacks side chasing a record fourth successive title in the annual
stoush of the southern hemisphere giants.
The South Africans, who cruised to world champion status last November, are largely intact while Australia have acquired Crusaders icon Robbie Deans as their coach, the man many believe should now be at the New Zealand helm.
But perhaps the greatest challenges for coach Graham Henry comes from within his own All Blacks squad, who have taken on a distinctly inexperienced tinge.
To maintain their winning standards of the past five years will mean handling the heaviest player turnaround of Henry's tenure, his stocks thinned appreciably by the lure of offshore riches.
And a clutch of off-field incidents, with halfback Jimmy Cowan a triple culprit, an injury to inspirational captain Richie McCaw and some mixed showings in their June tests suggest this is a New Zealand side ripe for the plucking.
They outmuscled Ireland in the Wellington big freeze and outclassed a dreary England twice, but Henry remains locked in a battle with public antipathy heightened by his selection policies last year and the World Cup flop.
Without McCaw, the onus falls on new captain Rodney So'oialo to lead a pack still oozing quality but now lacking depth in most positions.
Lock Ali Williams and prop Tony Woodcock are cornerstones, No 8 Jerome Kaino and lock Brad Thorn provide horsepower while we await some dynamic feats from unheralded flanker Adam Thomson.
In the backs, one player is the director and main actor rolled into one.
First five-eighth Daniel Carter's form since returning from injury midway through the Super 14 has been influential and he is the man the Springboks and Wallabies tacticians will have plastered all over their war rooms.
His guile is a contrast to the increasingly-skilled bowling ball Ma'a Nonu, who has claimed ownership of the No 12 jersey.
There are contests for selection among most of an outside back division which has been surprisingly fluent through the first three tests - admittedly against the, er, best of British back play.
South Africa are desperate to end their decade-long drought in New Zealand and will smell blood ahead of the two opening tests, in Wellington this Saturday and Dunedin a week later.
But the real story of this year's tournament was always going to be told on July 26, a date that was circled in red ink the moment Deans announced his Tasman Sea hop.
By the time the Wallabies face the All Blacks at Sydney, Deans would have had nearly two months to weave his own brand of magic.
It will be the first of four Bledisloe Cup tests but none will surely match the anticipation of Henry-Deans round one.
Victory in Sydney and twin home defeats of the Springboks would send New Zealand well on the way to a ninth title in 13 editions of the Tri-Nations.
But that sort of start resides in the very hard basket.
The Tri-Nations is traditionally relegated below the Bledisloe Cup, Grand Slam tours and Lions series in status but winning this nine-test, 11-week marathon one would rate among Henry's finest achievements.
- NZPA