MELBOURNE, Australia - The day after the Top 10 seeds progressed to the third round of a Slam for the first time in over a decade, upsets reigned at the 2020 Australian Open. The excitement and enormity of the underdog's wins from Tunisia's Ons Jabeur, China's Wang Qiang, and 15-year-old American phenom Coco Gauff were equally balanced by the heartbreaking exits for a retiring Caroline Wozniacki, 23-time major champion Serena Williams, and defending champion Naomi Osaka.

A colleague turned to me ahead of Osaka's press conference and asked what was the biggest story of the day. In truth, there was no right answer. All six women deserved significant ink, none more than the other.

As Serena and Wozniacki battled desperately, the former to prolong her quest for a record-tying 24th major title, the latter to prolong her remarkable career, their unrelenting opponents wove their own inspiring tales. For 25-year-old Jabeur, the stage was set for her pleasing, creative game and her own historic quest to become the first Arab woman to ever reach the Round of 16 at a major.

Over two hours and seven minutes, the affable Tunisian with a mercurial game that can crumble under its own craft and ambitious shot-making, poked and prodded the Dane's baseline game until one last forehand error spelled Wozniacki's doom. Jabeur prevailed 7-5, 3-6, 7-5 in a manner that even Wozniacki could only laugh about afterwards.

"I think it was only fitting that my last match would be a three-setter, a grinder, and that I would finish my career with a forehand error," Wozniacki said afterwards, before an emotional post-match celebration with her family on Melbourne Arena.

It was a hard-fought match and, in many ways, a symbolic moment. The trailblazer for Danish tennis bowed out to a trailblazer from Tunisia, another player who grew up hoping to make history.

"I had a dream when I was a kid," Wozniacki said. "I wanted to win a Grand Slam. I wanted to be No.1 in the world. People thought that I was crazy being from a small country. But I made it happen. I worked so hard for it every single day."

As Wozniacki draped her shoulders with the Danish flag as the Australian crowd serenaded her with one final rendition of "Sweet Caroline", her good friend Serena was on Rod Laver Arena struggling to understand how she had yet to pull away from a player she had defeated in 44 minutes just four months ago at the US Open.

In September, Serena faced off against China's No.1 Wang in the quarterfinals of the US Open and lost just one set in a lopsided 6-1, 6-0 win. On Friday afternoon, she had done what she's done so many times in the past. With her back against the wall in the second set, she broke Wang with ease when the 28-year-old stepped to the line to serve for the win at 5-4 in the second set and dominate the eventual tiebreak 7-2 to force a deciding set.

"I was optimistic I would be able to win," Serena said, when asked what her thoughts were going into the third set. "I thought, okay, now finish this off. I honestly didn't think I was going to lose that match."

The American looked primed to run away with the third set. But she had been able to break Wang's serve just once in the match, and Wang showed no signs of wobbling in the third set. Serena struggled to control her power all day - she finished the match with 56 unforced errors - and finally relented in the last game. Wang kept the pressure on the Serena service games with tireless court-coverage and inspired counter-punching, breaking Serena to win 6-4, 6-7(2), 7-5 in two hours and 41 minutes to make her first Round of 16 in Melbourne.

Serena put on a brave face afterwards but made it clear this loss, her earliest at a hardcourt Slam since 2006, hurt just as much as any other.

"I'm no happier than I was 10 years ago," Serena said. "But I just have to pretend like I don't want to punch the wall, but in reality I do.

"I'm way too old to play like this at this stage of my career. It's such a big tournament. It's no excuse, to be honest."

For Wang, this was redemption and a tribute to both her former coach, Australia's Peter McNamara, who passed away last year, and to her current coach, Thomas Drouet, who Wang says believes in her more than she sometimes believes in herself.

After her disappointing showing in New York, Wang said Serena's power game overwhelmed in every way and her solution was to get stronger and fitter. That was precisely her focus during her grueling off-season.

"In off-season we do three hours of tennis in a row," Wang said. "I think it really helped me to be stronger on the court, mentally tough on the court.

"My coach, Thomas, he always said, I believe 200% in you, so you must believe in yourself."

Wang's win came hours before a previously planned tribute to McNamara on Friday evening.

"I always dream about him," Wang said. "I think he can see what I play today. He will be proud of me. I really hoped he could be here, watch me play. I miss him."

While Melbourne Park was still recovering from the heart-racing theatrics of Jabeur and Wang's wins, Greece's Maria Sakkari finally broke her Grand Slam duck by upending an in-form 10th seed Madison Keys, 6-4, 6-4 to advance to her first Round of 16 at a Slam.

Then came the coda to a surprising day in which upsets spread virally across both draws, as Gauff played a pitch-perfect match to end Osaka's title defense. In the best performance of her young professional career, the American teen played an unflinching, aggressive match to defeat a flummoxed Osaka 6-3, 6-4 to advance to the Round of 16 at a Slam for the second time in her career.

Serving at over 75% first serves in and hitting flatter and deeper than she did in her 6-3, 6-0 loss to Osaka at the same stage in New York, Gauff never gave Osaka a chance to find her range. It was a tough night for Osaka, whose backhand broke down under pressure, and the World No.4 admitted the prospect of bowing out to a 15-year-old unnerved her.

"This one hurts a little bit more," Osaka said. "I love her, but I don't like this feeling of losing to her.

"Yeah, I feel bad for Wim, for my entire team, Nana, Abdul, Ka-ru. We came here to win the tournament, and I'm sort of the vessel that everyone's hard work is put into. And I wasn't able to do what I was supposed to do."

"It was one of those days where I couldn't do anything right, it felt like. My backhand, which is my more consistent side, every ball was flying. Even though I was telling myself, I know what to do in order for it to go in, it just wasn't going in.

"I don't know. I don't really have the champion mentality yet, which is someone that can deal with not playing 100%. I have always wanted to be like that, but I guess I still have a long way to go."

And so CocoMania lives on in Melbourne. We have seen Gauff scrap and battle to edge out wins and we have seen her handle big moments well. But against Osaka, Gauff never showed her age. There was no string of bad decisions, misfires, or straining to keep up. On this day, Gauff showed poise and focus from first ball to the last and played like a woman with full faith and confidence that she belonged.

"What is my life?" Gauff said on court, and you can think of no other player on tour right now who is living one more charmed.

"All these people clapping for me, every time I think people think you get used to it. I mean, I'm still new to this, but I'm sure I'm not used to it and I'm sure some of the players who have kind of already won a bunch of Slams, I'm sure every time that post-match walkout when you wave to the crowd, I'm sure they feel, like, unbelievable in that moment.

"Definitely that's definitely the mood for today, like, What is my life?"

After a funky Friday of results, here's how the Top Half Round of 16 shapes up:

[1] Ashleigh Barty vs. [18] Alison Riske
[22] Maria Sakkari vs. [7] Petra Kvitova
Coco Gauff vs. [14] Sofia Kenin
Ons Jabeur vs. [27] Wang Qiang

2020 Australian Open press conference: Osaka ‘You learn more when you lose’