Ash Barty has reached the fourth round of the Australian Open, but defending champion Naomi Osaka has been knocked out of the tournament by unseeded American Amanda Anisimova.
Barty progressed with a 6-2, 6-3 win over Italian 30th seed Camila Giorgi on Rod Laver Arena, with most observers feeling it was a mere formailty Osaka would be her opponent in the last 16.
But instead, it will be Anisimova, who scored a stunning upset victory over the four-time major winner, claiming a 4-6, 6-3, 7-6 (10-5) triumph on Margaret Court Arena.
Osaka had two match points when she led 5-4 in the third set, with the 60th-ranked Anisimova serving to stay in the contest.
Anisimova held serve before a super tiebreak was later needed to decide the match. The 20-year-old forced 13th-seeded Osaka to play catch-up early, always keeping her nose in front on the scoreboard.
She served for the match at 9-5, with an ace sealing the result and leaving the former world number one's title defence in tatters.
"I thought she [Anisimova] played really well," Osaka said after the match.
Anisimova — who had never played Osaka before Friday night — entered the tournament on the back of a WTA Tour event victory at Melbourne Park.
She said she was determined not to get carried away with her win, especially with Barty now her next opponent.
"I'm just enjoying one match at a time right now," said Anisimova, who recently included renowned Australian coach Darren Cahill in her support team.
"I don't think that I played amazing tennis today. I think it was a little bit tough, and I was pretty nervous.
"Hopefully I can build on this into the next round. My body is feeling good and I think that in the tough moments I was able to produce some good tennis.
"I'm feeling good, and I'm just enjoying every single match here."
Anisimova — who has been ranked as high as 21 — and Barty have previously played each other once, with Barty winning their 2019 French Open semifinal in three sets on her way to claiming her first major title.
This is the fourth year in a row that Barty has at least reached the last 16 of the Australian Open.
She wrapped up her match against Giorgi while Anisimova and Osaka were battling their way through the third set of their encounter.
"I would have loved to have had the opportunity to play Naomi," Barty said at her post-match media conference.
"I love to test myself against the very best.
"In the position we're in, Amanda has played a fantastic tournament. She deserves her spot in the round of 16. I think the match we will play will be exciting.
Barty said she had vivid memories of her previous on-court meeting with Anisimova.
"I remember the biggest moment of that match was coming out of the chair at 3-0 down the second set," she said.
"I remember that to this very day, what I was saying to myself at that change of ends. From then on, it's held me in pretty good stead, sticking to those values and continuing to try and grow each and every time on court.
"It hasn't worked every time, but it's made me really comfortable and made me feel like I belong out on the court.
"I get to do it my way. I get to be unique. I get to experiment and I get to have fun with it."
Barty dominates Giorgi early
On Friday night, Barty and Giorgi did not take the court until almost an hour later than scheduled. The final match of the day session — between Matteo Berrettini and Carlos Alcaraz — stretched past four hours and needed a fifth set to decider the winner.
The delay did not seem to bother Barty, who held serve in the first game and then broke Giorgi for a 2-0 lead.
Barty's dominance of her opponents' serves in her opening two matches helped paved the way for both victories and it seemed Giorgi was facing as much pressure.
But the Italian won her next service game to love, easing her nerves considerably.
Later in the set, Giorgi came close to landing a blow on Barty when she had four break points during the seventh game with the Australian leading 4-2.
Giorgi's powerful groundstrokes from the baseline left Barty scrambling to return at times, however emotionally she was unperturbed.
The Wimbledon champion calmly served out the game to hold for a 5-2 lead, before breaking Giorgi for a second time to claim the set in 32 minutes.
Neither player was threatened on serve early in the second set, although Barty attracted a collective gasp from the crowd when she produced a double fault at 40-0 in the fifth game.
As if to reassure her fans all was OK, she fired down an ace the very next point to go up 3-2.
The decisive moment of the set came in the following game when Barty broke Giorgi. She could see the finish line and soon served for the match at 5-3, which she did to love to ice victory in just over an hour.
"I think tonight I did a really good job of just trying to nullify the areas where Camila could hurt me," Barty said.
"I was able to put her in trickier positions of the court that just made it harder for her to hurt me with her weapons, and I think that was a big part of tonight."
