Wales produced an excellent performance for 55 minutes only to be left shocked by a remarkable comeback from Australia, who secured a 39-34 triumph in Cardiff.
Wayne Pivac’s men played with tempo, intensity and physicality for the first hour, scoring four tries via Jac Morgan, who went over twice, Taulupe Faletau and Rio Dyer.
A weakened Wallabies side looked dead and buried but the visitors displayed tremendous spirit to respond.
Youngster Mark Nawaqanitawase was excellent throughout and began the fightback by touching down in the 58th minute before adding another 10 minutes later.
A penalty try reduced the arrears further before Lachlan Lonergan crossed the whitewash as Australia snatched an unlikely win.
Whether Pivac remains in charge heading into this season’s Six Nations Championship now looks unlikely, with Wales’ woes continuing just 10 months before the World Cup in France.
Pivac handed a Test debut to Ospreys centre Joe Hawkins, while world record cap holder Alun Wyn Jones made his first Wales start since March.
But a late injury blow saw full-back Leigh Halfpenny ruled out after he suffered a back spasm during the warm-up, so wing Josh Adams was promoted off the bench and handed the number 15 shirt.
Wales made a poor start, with lock Adam Beard dropping the kick-off, Australia dominating an ensuing scrum and Ben Donaldson booting his team ahead through a third-minute penalty.
But the home side hit back impressively, as scrum-half Tomos Williams linked well with Jones, whose one-handed pass found Morgan, and he powered over for his third try in two Tests.
Gareth Anscombe converted, before Williams went off for a head injury assessment and was replaced by Kieran Hardy.
Donaldson and Anscombe exchanged penalties as Wales led 10-6 after the opening quarter, and there was an impressive momentum about Pivac’s team.
Australia then fell further behind following a slick handling move that ended in Faletau crossing wide out after he collected wing Dyer’s scoring pass.
Anscombe converted and added another penalty, putting Australia firmly behind the eight-ball as they trailed by 14 points midway through the second quarter.
Australia needed a response before the interval, and it arrived through a 33rd-minute try for Fainga’a after the Wallabies executed an impressive lineout drive.
Donaldson converted, but Australia had scrum-half Jake Gordon yellow-carded for deliberate offside following a sharp Dyer break.
Wales could not make them pay, though, with Hardy being held up over the line, and Australia trailed 20-13 at half-time.
Australia then briefly went down to 13 men when replacement prop Tom Robertson, who was on for Wallabies skipper James Slipper, received a yellow card following a scrummaging infringement.
A driving maul rumbling towards the line is a thing of beauty. 😍pic.twitter.com/Ilqw2oGohg
— Planet Rugby (@PlanetRugby) November 26, 2022
And Wales made it count, driving a lineout at relentless pace, with Morgan claiming his second try and Anscombe’s conversion restoring a 14-point advantage.
Australia could not handle a rampant Welsh pack, and Dyer scored Wales’ fourth try, with Anscombe converting before he went off after suffering a nasty-looking shoulder injury.
But the game was turned on its head during a scarcely believable final quarter, with Nawaqanitawase’s second try prompting a Welsh collapse as Justin Tipuric was sin-binned for a trip and Elias followed after he collapsed a maul that led to the penalty try.
And there was still time for Lonergan to win a game that was probably Pivac’s 34th and final Test in charge of Wales.