Melbourne - America's Serena Williams suffered a stunning third-round defeat to China's Wang Qiang at the Australian Open on Friday, pushing Margaret Court's 47-year-old record for career Grand Slam titles further from her grasp.
Williams, 38, was the bookies' favourite to win a record-equalling 24th Major at Melbourne Park but she came unstuck against a determined Wang, who won 6-4, 6/7 (2/7), 7-5 - after taking only one game last time they met.
The upset means Williams, whose last Major win was at the 2017 Australian Open when she was pregnant, has fallen short at eight Grand Slams - including four finals - since returning from having her baby.
It further extends her long quest to equal Court, 77, who is in Melbourne this week to celebrate the 50th anniversary of her 1970 calendar-year Grand Slam.
Williams' defeat came just minutes after her close friend Caroline Wozniacki was knocked out by Tunisia's Ons Jabeur, bringing a tearful end to the former world number one's final tournament before retiring.
"I honestly didn't think I was going to lose that match," said Williams, adding that she still believed she would win an elusive 24th Major.
"I definitely do believe or I wouldn't be on tour," she said.
The shock result removes a major hurdle for Australia's world number one Ashleigh Barty, who had been on course to meet Williams in the semi-finals and moved smoothly into round four.
Barty, bidding to become the first Australian champion since 1978, hit form in a 6-3, 6-2 demolition of Elena Rybakina, saying she had played her best tennis so far this year.
"I felt I needed to be really switched on for this," she said. "I feel it's the best I've played this summer so far."
Wang, the 27th seed, was walloped 6-1, 6-0 by Williams in last year's US Open quarter-finals, triggering a torrent of criticism from Chinese fans at the manner of the defeat.
But even after failing to serve out the match in the second set, the 28-year-old steeled herself and she broke Williams for the third time to claim the biggest scalp of her career.
"I think my team always believed I can do it," said Wang. "After last time I did really hard work on and off court, I believed I could do it."
Williams, seeded eight, started slowly against the fast, positive Wang, and it looked all over when she was a set and a break down with Wang serving for the match.
However, Williams won a titanic 24-shot rally to break the Chinese player for the first time, raising her arms in triumph, and dominated the tie-breaker to level the match.
In the tense final set, both players held firm but Wang pounced when Williams was serving to stay in it, converting her third match point as the American netted.
Later, Roger Federer will need to avoid a second Grand Slam upset at the hands of home favourite John Millman, after the 2018 US Open, if he wants to bring up 100 wins at the Australian Open on Friday.
Reigning men's champion Novak Djokovic, who dismissed Tatsuma Ito in round two, thrashed another Japanese opponent, Yoshihito Nishioka, 6-3, 6-2, 6-2 to make the round of 16.
And huge interest surrounds the meeting later between 15-year-old American Coco Gauff and defending champion Naomi Osaka, 22, the second instalment of a rivalry that could run and run.
Serena Williams was knocked out of the Australian Open in the third round by China's Wang Qiang on Friday, destroying her bid for a record-equalling 24th Grand Slam crown.
Serena Williams' failed attempts at history since winning the Australian Open in 2017 while pregnant:
French Open 2018
- Pulled out of her fourth-round clash with Maria Sharapova with a pectoral injury in her first Slam since having a baby.
- An error-strewn Williams defeated in the final by Angelique Kerber, 6-3, 6-3, the German's maiden Wimbledon title and third Grand Slam crown.
US Open 2018
- Beaten 6-2, 6-4 by Japan's Naomi Osaka in a controversial and emotional final that left both players in tears.
Australian Open 2019
- Squandered four match points and a 5-1 third-set lead against Karolina Pliskova to crash out in the quarter-finals 6-4, 4-6, 7-5.
French Open 2019
- Upset in the third round 6-2, 7-5 by unseeded American Sofia Kenin, her worst Grand Slam exit since Wimbledon in 2014, when she fell at the same hurdle.
- Destroyed 6-2, 6-2 in just 56 minutes in the final by Simona Halep in perhaps the Romanian's finest performance.
US Open 2019
- Toppled by teenager and 15th seed Bianca Andreescu in a rollercoaster 6-3, 7-5 final in a performance Williams called "inexcusable".
Australian Open 2020
- Sensationally dumped out by Chinese 27th seed Wang Qiang.
Results on day five of the Australian Open Grand Slam at Melbourne Park on Friday (x denotes seeding):
Marton Fucsovics (HUN) bt Tommy Paul (USA) 6-1, 6-1, 6-4
Diego Schwartzman (ARG x14) bt Dusan Lajovic (SRB x24) 6-2, 6-3, 7-6 (9/7)
Novak Djokovic (SRB x2) bt Yoshihito Nishioka (JPN) 6-3, 6-2, 6-2
Ashleigh Barty (AUS x1) bt Elena Rybakina (KAZ x29) 6-3, 6-2
Petra Kvitova (CZE x7) bt Ekaterina Alexandrova (RUS x25) 6-1, 6-2
Ons Jabeur (TUN) bt Caroline Wozniacki (DEN) 7-5, 3-6, 7-5
Alison Riske (USA x18) bt Julia Georges (GER) 1-6, 7-6 (7/4), 6-2
Maria Sakkari (GRE x22) bt Madison Keys (USA x10) 6-4, 6-4
Wang Qiang (CHN x27) bt Serena Williams (USA x8) 6-4, 6-7 (2/7), 7-5
The moment of a LIFETIME!— #AusOpen (@AustralianOpen) January 24, 2020
Qiang Wang puts on an absolute masterclass in the match of the tournament to shock Serena Williams 6-4 6-7(2) 7-5 and advance to a first career #AusOpen round of 16.#AO2020 pic.twitter.com/gnGkAMaU8X