After posting only 163, Australia were then punished in the field by Pakistan openers Saim Ayub (82) and Abdullah Shafique (64 not out) as the tourists raced to a nine-wicket victory in the second ODI with 141 balls to spare.
It is the first time since 1992 Australia have lost a home ODI by nine wickets.
They avoided becoming the first Australian team to lose a white-ball match at home by 10 wickets when Adam Zampa ended the 137-run opening stand.
Saim Ayub smashed six sixes in his 82 runs. (Matt Turner/AAP PHOTOS)
"Wasn't one of our best days," Australia captain Pat Cummins said.
"We've been pretty good of late, but today was right up there with one of our worst, unfortunately."
Pakistan's stunning triumph on Friday gives them a huge opportunity to win the three-match series, with Test stars Cummins, Mitchell Starc, Josh Hazlewood, Steve Smith and Marnus Labuschagne to sit out Sunday's deciding game in Perth.Â
Those five won't make the trip west so they can prepare for the upcoming battle for the Border-Gavaskar trophy against India.
Wicketkeeper Josh Inglis, who will captain Australia for the first time in Cummins' absence, Glenn Maxwell, and Zampa will be the only members of last year's World Cup final side to play at Optus Stadium.
Pakistan's first ODI win against Australia at the Adelaide since 1996 was set-up by tearaway quick Haris Rauf, who demolished the middle-order.
Rauf, who has been a popular figure in the Big Bash League for the Melbourne Stars since 2020, picked up where he left off at the MCG when Pakistan captain Mohammad Rizwan won the toss and opted to bowl.
The 31-year-old gave Pakistan a chance of a shock victory on Monday with 3-67, before Cummins steered Australia home by two wickets.
But Rauf (5-29) went to another level in Adelaide with his second five-wicket haul in ODIs, dismissing Josh Inglis, Marnus Labuschagne, Aaron Hardie, and Glenn Maxwell as Australia collapsed from 2-79 to 7-129.
The fiery right-armer also claimed Cummins' scalp to end any chance Australia had of posting a competitive total.
Rauf finished with the best ODI figures by a Pakistani bowler at the Adelaide Oval, impressing the legendary Wasim Akram in the commentary box.
Abdullah Shafique helped Pakistan level the series with an enterprising 64 not out. (Matt Turner/AAP PHOTOS)
Australia should have been all-out for 147 but wicketkeeper Rizwan spilled a skied ball from Zampa.
Zampa belted a quick-fire 18, even goading Rizwan into, unsuccessfully, using a review, saying: "You blokes appeal for everything. You should take it (the review)."
Steve Smith finished as Australia's top-scorer with 35 when their innings ended in the 35th over.
Australian openers Matt Short (19) and Jake Fraser-McGurk (13) failed to silence critics of their cavalier batting.
Australian great Ian Healy had called the pair "schoolyard bullies" and urged them to temper their aggression.
On Thursday, Fraser-McGurk said he would continue batting his way.
*AUSTRALIA'S BIGGEST ODI CRICKET LOSSES, BY WICKETS
10 wickets v New Zealand, Wellington 2007
9 wickets v West Indies, SCG 1984
9 wickets v West Indies, Kingston 1984
9 wickets v South Africa, SCG 1992
9 wickets v West Indies, WACA 1992
9 wickets v Pakistan, Rawalpindi 1994
9 wickets v West Indies, St George's 2003
9 wickets v England, Headingley 2005
9 wickets v India, Jaipur 2013
9 wickets v Pakistan, Lahore 2022
9 wickets v Pakistan, Adelaide Oval 2024
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