The defeat ended Williams's bid for a record-equalling 24th Grand Slam title.
Serena displayed great mobility to win successive points after long rallies -- one of 21 shots, one of 13 -- and secure what proved to be a decisive break of serve.
Victoria Azarenka refuses to accept that Maria Sharapova's greater experience could be the defining factor when they meet in the Australian Open women's final on Saturday.
Defending champion and world number one Novak Djokovic won his third-straight Australian Open crown, his ninth in total.
A resurgent Svetlana Kuznetsova stunned former World No. 1 Caroline Wozniacki in an absorbing encounter on Rod Laver Arena to reach the quarter-finals of the Australian Open with a 6-2, 2-6, 7-5 victory on Monday.
Images from Day 1 at the Australian Open.
Novak Djokovic kicked off his season in style with a 7-5, 7-5 win over Canadian talent Denis Shapovalov on his favourite Rod Laver Arena court on Tuesday before returning to lead Serbia to a doubles victory that sealed their ATP Cup opener 2-1.
Nadal said he did not expect to go all the way at Melbourne Park
After two years in the spotlight as Australian Open champion, Victoria Azarenka was reduced to a spectator against Agnieszka Radwanska as she crashed out of the quarter-finals in a bout of self-flagellation on Wednesday.
Barty is primed to become the first local since Chris O'Neil in 1978 to win the Australian Open.
Images from Day 3 of the Australian Open in Melbourne on Wednesday.
Andy Murray embarks on his first Grand Slam campaign as world number one with much stronger title credentials, even if he has lost five finals at Melbourne Park.
Li Na wore down Agnieszka Radwanska with a barrage of power-hitting to beat the fourth seed 7-5, 6-3 and advance to her third semi-final at the Australian Open on Tuesday.
Silent assassin Agnieszka Radwanska ended Victoria Azarenka's bid for a hat-trick of titles at Melbourne Park on Wednesday and reached her maiden Australian Open semi-final with a 6-1, 5-7, 6-0 win.
Heartbroken by Djokovic in two five-set epics in Melbourne and the US Open last year, the eighth-seeded Swiss played out of his skin to upset his Grand Slam nemesis 2-6, 6-4, 6-2, 3-6, 9-7 in an exhilarating four hours.
The Australian Open will lose one of its giant killers when South Korean Chung Hyeon meets American Tennys Sandgren in an unlikely quarter-final showdown at the Rod Laver Arena on Wednesday.
Third seed Maria Sharapova was dumped out of the Australian Open on Monday with a 3-6, 6-4, 6-1 fourth round loss to Slovakia's Dominika Cibulkova on Rod Laver Arena.
Picking up her racquet bag and marching straight out of Rod Laver Arena without a nod or a wave, Maria Sharapova's abrupt exit after her fourth-round loss to Dominika Cibulkova on Monday spoke volumes of her disdain for a forgettable Australian Open.
Serena Williams admitted that a bad back sustained during practice hampered her movement during her shock fourth round loss to Ana Ivanovic on Sunday, but refused to blame the injury for her stunning exit that blew the Australian Open wide open.
Images from the Australian Open matches played on Sunday.
Serbia's Ana Ivanovic stunned World No 1 Serena Williams at the Australian Open on Sunday with a 4-6, 6-3, 6-3 fourth-round upset at Rod Laver Arena.
Images from the Australian Open matches played in Melbourne on Saturday.
Images from the Friday's play at the Australian Open.
Victoria Azarenka said the prospect of winning a third straight Australian Open title is an inspiration, not a pressure, after booking her place in the third round.
The thought of playing a long match in the extreme Melbourne heat resulted in a sleepless night for Serena Williams, but the World No 1 need not have worried as she strode swiftly into the Australian Open third round on Wednesday.
Images from the Australian Open matches played in Melbourne on Tuesday.
World number one Nadal made the announcement at Melbourne Park's Rod Laver Arena during the "Rally for Relief" event.
Novak Djokovic will need to spend some time on the sidelines recovering from a muscle tear that hindered him in the later rounds of the Australian Open, the Serbian said as he celebrated his ninth Melbourne Park title on Monday.
Beaten in just over two hours, Nadal won barely a third of the match's points, was broken five times and conjured only a single break point in the third set, which the Serb saved.
Brady saw four match points slip through her fingers as she served it out nervously but finally celebrated the win when Muchova fired a forehand long.
Fire-fighters went on alert as the mercury crept towards an expected maximum of 44 degrees Celsius (111 F), the highest since Black Saturday bushfires in 2009 that killed about 180 people in the southeastern state of Victoria.
Images from Sunday's action at the Australian Open in Melbourne.
Stefanos Tsitsipas credited his stellar comeback win against Rafa Nadal in Wednesday's Australian Open quarter-final to his peace of mind, saying he had attained a state of "nirvana" during the match despite falling back by two sets.
Defending champion Victoria Azarenka suffered a panic attack trying to close out her Australian Open semi-final against American teenager Sloane Stephens on Thursday and needed a long medical timeout before setting up a final against Li Na.
Images from Day 8 of the 2022 Australian Open at Melbourne Park on Monday.
Defending champion Novak Djokovic returns to the Australian Open seeking his third consecutive trophy at Melbourne Park, where memories of last year's gut-wrenching final against Rafa Nadal still linger around Rod Laver Arena's blue centre court.
Images from Monday's action at the Australian Open.
Fifth seed Ana Ivanovic was knocked out of the Australian Open first round on Monday when she was upset by doubles specialist Lucie Hradecka 1-6, 6-3, 6-2.
Serena Williams ended the fairytale run of Mirjana Lucic-Baroni at the Australian Open on Thursday with a crushing 6-2, 6-1 win that set up a final against her sister Venus.
Images of the Day 11 of the Australian Open.