Having beaten Italy, England and France on their November travels, the Wallabies were seeking to make it four out of four in Europe in a game that marked the centenary of fixtures between the two nations.
And just as they had done in the very first meeting on 12 December, 1908, Wales came out on top to carry off the James Bevan Trophy for the first time since it was awarded in 2007.
A crowd of 74,314 roared Wales onto the victory they craved so much this autumn having come up short against the Springboks and the All Blacks. Ryan Jones' team led 15-10 at the break thanks to tries from Shane Williams and Lee Byrne and then kept their noses in front throughout the second half thanks to a drop goal and penalty from Stephen Jones.
"It was a real contest out there. It was a good performance from Wales and very much what we expected from them," said Deans.
"I think Wales are better equipped than the other countries to go into the Six Nations in the new year and do well. If you look at the number of line-breaks they created, and look at their resilience, they have all the attributes that serve you well as a team.
"They should take a lot of belief and confidence out of being the only European side to beat a southern hemisphere team this autumn.
"Warren Gatland has made a big difference to them and they are a better team now than when they won the Grand Slam. They are playing good rugby, playing with width and ambition and they push the boundaries in defence.
"Their conditioning has improved, their collective understanding is better and they are working hard together to play better rugby.
"Over the past three weeks they have proved they can challenge the southern hemisphere sides."
All the talk in the Welsh camp over the past month had been about turning potential into a victory over one of the southern hemisphere giants and the result they wanted finally came in the last game.
The game got off to an explosive start with a huge midfield collision between Aussie skipper Stirling Mortlock and Wales centre Jamie Roberts forcing Mortlock to leave the battle after only two minutes.
Roberts battled on to play a key role in the first Welsh try a minute later, but was forced to retire in the 17th minute when he began complaining of headaches. He was sent to hospital where it was discovered he had played 15 minutes with a fractured skull.
Despite dominating the opening exchanges, and giving newly crowned IRB Player of the Year Williams an easy run in for his 44th Test try, Wales coughed up their third soft try of the series.
They won a line-out on the Wallaby 10 metre line, but lost control of the delivery. The ball bounced into the arms of Mark Chisholm and he ran half the length of the field to score a try which Matt Giteau converted.
Giteau then dropped a goal to extend the lead before a Stephen Jones penalty and Byrne try returned the advantage to the home side. It was Williams who sent Man of the Match Byrne racing to the posts for his try and Jones added the simple conversion.
There were two bad penalty misses from the Welsh No 10 at the start of the second half and Giteau cut the gap to two points with a successful penalty of his own.
But Jones made amends with a 67th minute drop goal and a 78th minute penalty
Those kicks seemed to have made the game safe, but the Wallabies worked Digby Ioane over for a try on the stroke of time that gave Wales one final offence to defend form the re-start.
They held their line and finally took the scalp they wanted.
Scorers: Wales: Tries: Shane Williams, Lee Byrne; Con: Stephen Jones; Pens: Stephen Jones 2: DG: Stephen Jones. Australia: Tries: Mark Chisholm, Digby Ioane; Con; Matt Giteau; Pen: Matt Giteau; DG: Matt Giteau.