Australia (17) 34
Tries: Cross, Hynes, Elsom, Horwill Cons: Giteau 4 Pen: Giteau Drop: Giteau
New Zealand (12) 19
Tries: Muliaina, Hore, Ellis Cons: Carter 2
Ryan Cross scored the first of Australia's four tries
Australia extended Robbie Deans' unbeaten start as coach with victory over his native New Zealand in a superb Tri-Nations clash in Sydney.
The Wallabies led 17-12 at half-time with converted tries from Ryan Cross, on his full debut, and Peter Hynes.
The All Blacks replied with scores from Mils Muliaina and Andrew Hore before the interval, and took the lead when Andy Ellis crossed on the resumption.
But Australia hit back with tries from Rocky Elsom, and James Horwill late on.
Victory maintained the Wallabies' unbeaten start to the tournament as they racked up their fifth win in a row overall under Deans, who many New Zealanders felt should have replaced his All Blacks counterpart Graham Henry after the World Cup.
The hosts started strongly in the old Olympic Stadium and were 10-0 to the good within the first 10 minutes.
Giteau landed an early penalty before Cross, starting his first Test in place of injured skipper Stilring Mortlock, had an easy run-in after Lote Tuqiri burst through three tackles, Giteau adding the extras.
It was a great defensive effort from the boys, a real gutsy win
Stand-in Aussie captain George Smith
All Blacks lock Brad Thorn was already off the field by that stage, sin-binned for a high tackle on Giteau.
But the visitors hit back with a try from Muliaina in the 23rd minute, the full-back breaking clear down the right, chipping ahead and then gaining his reward when the ball bounced fortuitously out of Australian hands.
The Wallabies responded with a superb second try of their own, an excellent grubber kick from Adam Ashley-Cooper toed on by Tuqiri, Hynes dotting down and Giteau's conversion making it 17-5.
But New Zealand replied with two tries either side of the interval to snatch the lead.
First, in the last move of the first half, hooker Hore ran back across the Australian defensive line through three would-be tacklers to score, Carter's conversion reducing the half-time deficit to 17-12.
Within five minutes of the resumption the All Blacks were ahead, Carter stepping off his right foot to cut a swathe through the Wallabies defence, Ma'a Nonu taking it on and Ellis pirouetting over from close range.
Carter's conversion made it 19-17, and replacement scrum-half Jimmy Cowan saved a certain try when he dived at Tuqiri's feet before Australia regained the advantage.
Cowan's clearing kick failed to find touch, and flanker Elsom bounded through a gaping hole from 20m out, Giteau's conversion making it 24-19.
We made too many mistakes. Against a team like Australia, you get punished
Stand-in NZ captain Rodney So'oialo
Cowan was forced off with a knee injury, and after some confusion amongst the match officials, Ellis was allowed to return to the field.
Giteau's smart drop-goal with 13 minutes left gave the Wallabies some breathing space, and when lock Horwill plunged over with six minutes left, the game was up for the All Blacks.
It is the first time they have lost two consecutive Tests (after a home loss to South Africa) since 2004, and heaps the pressure on Henry ahead of the return fixture next Saturday.
Australia, who now lead the Tri-Nations standings with nine points from two games, could claim the Bledisloe Cup for the first time since 2003 with victory in Auckland, and also have the incentive of overtaking the All Blacks at the top of the world rankings.
"That was a good mental test but they got up and got on the front foot and finished strongly," said Wallabies coach Deans. "Obviously there's enough belief there for them to keep going."
Australia: Ashley-Cooper, Hynes, Cross, Barnes, Tuqiri, Giteau, Burgess; Robinson, Moore, Baxter, Horwill, Sharpe, Elsom, Smith (capt), Palu.
Replacements: Polota-Nau, Dunning, Vickerman, Waugh, Cordingley, Tahu, Mitchell.
New Zealand: Muliaina, Tuitavake, Kahui, Nonu, Sivivatu, Carter, Ellis; Woodcock, Hore, Somerville, Thorn, Williams, So'oialo (capt), Braid, Kaino
Replacements: Mealamu, Afoa, Boric, Lauaki, Cowan, Donald, Smith.
Referee: Craig Joubert (South Africa)