Shane Williams scored a try with his final touch for Wales as the veteran wing bade an emotional farewell to international rugby.
But it was not a winning farewell in his 87th cap for the 34-year-old Ospreys star, as Australia repeated their victory in the recent World Cup bronze medal match.
Second-half tries by scrum-half Will Genia and wing Lachie Turner - scored in quick succession after Wales full-back Leigh Halfpenny had been sin-binned for tackling James O'Connor without the ball - were followed by a Berrick Barnes touchdown.
The damage was inflicted during a ruthless 12-minute spell when Australia took control and silenced a 69,000 crowd at the Millennium Stadium.
O'Connor kicked three conversions and a penalty, while Wales could only muster tries from Williams and Rhys Priestland, two Priestland penalties and a Dan Biggar conversion.
Wales showed six changes from the side beaten by Australia at the World Cup, some of them enforced as injuries sidelined locks Alun-Wyn Jones and Luke Charteris, prop Adam Jones and centre Jonathan Davies, while French club commitments accounted for half-backs James Hook and Mike Phillips.
Cardiff Blues prop Scott Andrews made his first Test start and Ospreys lock Ian Evans returned following an injury-ravaged three years out of international rugby, but Australia also had some notable absentees in star World Cup backs Kurtley Beale and Quade Cooper.
A minute's silence, which broke into spontaneous applause, was held before kick-off in memory of the late Wales football manager Gary Speed, and the opening exchanges proved low key.
It took 13 minutes for Williams to receive his first pass, but it was of such poor quality from centre Scott Williams that it rolled along the floor and the celebrated wing knocked on.
Unlucky
Priestland had already kicked Wales ahead through a 45-metre penalty, but Australia had their moments and were unlucky not to strike after Priestland saw his attempted defensive clearance charged down by opposite number O'Connor.
Wales escaped on that occasion, and they enjoyed another reprieve when O'Connor sent an angled penalty chance wide from 25 metres eight minutes before half-time.
Australia, though, continued to press and they looked to have finally breached Wales' well-organised defence courtesy of Barnes' cross-kick aimed towards Turner.
Turner grounded the ball over Wales' line, but a last-ditch Shane Williams tackle nudged him into touch a split second beforehand, and Wales regrouped for Priestland to kick his second penalty.
O'Connor cut the deficit with the final scoring act of a disjointed opening period, although Wales probably just about deserved their 6-3 advantage.
Wallabies coach Robbie Deans
made an interval change, taking off openside flanker David Pocock and replacing him with Radike Samo, and there was a greater urgency about Australia's approach.
made an interval change, taking off openside flanker David Pocock and replacing him with Radike Samo, and there was a greater urgency about Australia's approach.
Halfpenny's yellow card then played right into their hands, and he had hardly left the field before Genia sniped his way over from close range for a try that O'Connor converted.
It was rough justice on Wales, but they had to regroup quickly, and they were helped when O'Connor hit the post from close range with a penalty that would have extended Australia's lead.
But the Wallabies had momentum, and with Halfpenny still off, a slick handing move ended in Turner sprinting over wide out and O'Connor booted the touchline conversion.
Barnes then ended the game as a contest, and although Priestland touched down 13 minutes from time before Williams crossed during the closing seconds, Wales had crucially conceded 21 second half points.
