The injury-ravaged Wallabies have fallen to their third straight loss, going down 13-10 to world No.1 Ireland in Dublin in another thrilling contest.
The Australians opted to go for a match-winning try in the 78th minute rather than tie up the result with a penalty kick.
But they were then penalised themselves for a technical offence as they tried to maul the ball.
They had one last chance but turned the ball over, allowing Ireland to kick the ball into touch to secure the victory.
Coming off a historic first loss to Italy, the Wallabies responded in style and were level with the top-ranked team until the 77th minute, when Ireland replacement five-eighth Ross Byrne kicked a penalty.
They showed some grit to keep Ireland tryless until the 66th minute, when replacement centre Bundee Aki barreled across the line.
The Wallabies levelled in the 72nd minute after Jordan Petaia showed his class to glide through a gap to score, with Bernard Foley adding the extras.
Ireland lost veteran skipper and playmaker Johnny Sexton to a calf injury in the warm-up with Jack Crowley starting.
But the Wallabies' 2022 horror injury toll continued to mount with prop Taniela Tupou assisted from the field in a medi-cab after suffering a second-half leg injury.
The Wallabies also lost centre Hunter Paisami to a knee injury in the fourth minute and hooker Dave Porecki to a head knock 20 minutes later.
Barnstorming No.8 Rob Valetini also limped off early in the second half.
The Australians' discipline again proved costly, denying them a third-minute try while their replacement hooker Folau Fainga'a was yellow-carded for a neck roll late in the first half after repeated team warnings about foul play by referee Ben O'Keeffe.
Halfback Nic White looked to have opened the scoring when he darted through a hole but the TMO spotted a neck roll by Porecki on Josh van der Flier and the try was disallowed.
With Porecki already off, Folau's yellow card meant with no available hookers the Wallabies were forced to play with 13 players and uncontested scrums for two minutes early in the second half.
But they managed to keep Ireland from crossing the line, with White and Foley tackling Australian-raised Ireland winger Mack Hansen into touch as he flung a pass in-field.
After Tupou's exit the Wallabies levelled at 3-3 through a scrum penalty, with Foley on target after an easy first-half miss.
Ireland went ahead through Aki in the 66th minute before a massive Will Skelton carry put the Wallabies on the front foot for Petaia's try four minutes later to set up a thrilling finale.