Australia's rugby women had been coming a humbling defeat at Ireland in Belfast at the weekend, but they were far sharper on Friday night (Saturday AEST) as they matched the home side in a dramatic contest.
But with the game tied at 24-24, Kate Williams crashed over from close range with the last attack of the night to give the hosts a famous victory, their first in seven attempts over Australia.
In a closely-fought first half, Maya Stewart, the Wallaroos' flying winger scoring for the second international in a row, and Welsh captain Keira Bevan had both gone over for tries.
Australia had a fine solo effort from Ashley Marsters then ruled out after replays showed the hooker had been in front of the ball at the breakdown, meaning the sides went in at halftime locked at 7-7.
After the break, Wales' Molly Reardon then scored twice, either side of a landmark try for Australia's teenage fullback Caitlyn Halse.
Alisha Joyce-Butchers looked to have put the match beyond Australia with her try, but powerful No.8 Tabua Tuinakauvadra ploughed over the whitewash for the visitors.
When Arabella McKenzie then converted nervelessly with three minutes remaining, it looked as if the Wallaroos would get at least a hard-earned draw.
But Wales were having none of it, going for the jugular with one last series of pick-and-gos, eventually grabbing their historic win with the clock in the red when Williams piled over much to the joy of the home crowd.
The Australians will get a quick shot at revenge in eight days time when the teams meet again in their WXV2 opener in Cape Town.
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