Wales march into quarter-finals after battering Wallabies towards World Cup exit
Scrum half Gareth Davies, centre Nick Tompkins and flanker Jac Morgan scored tries with replacement fly half Gareth Anscombe banging over six penalties, a conversion and a drop goal to give the Welsh a third win in three Pool C matches.
The Wallabies, stunned by Fiji last week, lacked nothing in endeavour but made too many mistakes and were outclassed by a streetwise Welsh side, who backed their defence, managed the game expertly and ruthlessly made the most of their chances.
Eddie Jones's young team, who managed only two early Ben Donaldson penalties, still have a mathematical chance of getting into the knockout rounds but would need Fiji to lose at least one of their last two pool matches against Georgia and Portugal.
The game could not have started worse for the Wallabies, who were penalised at the first breakdown and a try down in under three minutes after Wales captain Morgan burst through the midfield and offloaded for Davies to score.
Australia immediately tested the Welsh defence through multiple phases and came away with a Donaldson penalty in the ninth minute and another in the 14th as the result of a dominant scrum.
Wales fly half Dan Biggar was injured in an early tackle and replaced by Anscombe, who missed his first attempt at goal but nailed the next three to extend the lead to 16-6 at half time.
Anscombe added another penalty just after the break then chipped a lovely ball over the top of the Australian defence to send Tompkins in for the second Welsh try and extend the lead to 20 points with 48 minutes on the clock.
The Wallabies scored 26 unanswered points in a comeback win over Wales in Cardiff last November but there was to be no repeat in Lyon.
Anscombe drilled two more penalties in the 52nd and 60th minutes and then, with Wales going through the phases without making much progress, slotted a drop goal with 10 minutes left on the clock.
Fly half Carter Gordon, dropped for the match but on as a replacement, summed up Australia's night when he tried to kick for touch in the 75th minute only to send the ball out behind the goals.
With the Welsh crowd favourite "Hymns and Arias" echoing around OL Stadium, there was still time for Wales to roll a maul over the line and give Morgan a well-deserved try.