MELBOURNE, Australia -- If there was ever a day to wear running shoes to Melbourne Park, middle Sunday was it.
The day opened on Rod Laver with No. 8 Petra Kvitova taking on 17-year-old American Amanda Anisimova, the youngest player remaining in the tournament. Before Sunday, Anisimova -- who had never won a Grand Slam match before this week -- was 1-0 against Kvitova, having defeated her in the third round at Indian Wells last year. But the two-time Wimbledon champ was prepared for the teen this time around; she needed less than an hour to end Anisimova's fairytale run in straight sets.
"There's always pressure when you're the favorite and the young players are playing fearless and have nothing to lose," Kvitova said after her fourth-round win. "I remember that from when I was younger. I knew it would be a tough match for me."
Before Kvitova had completed her on-court interview -- which could have served as a warning for the favorites playing on the other show courts -- drama began brewing on Melbourne Arena, as unseeded American Frances Tiafoe started his 21st birthday celebration by taking the first set from No. 20 Grigor Dimitrov, a quarterfinalist here last year.
But wait ... back on Rod Laver Arena, top-ranked Australian Ashleigh Barty was pushing world No. 30 Maria Sharapova to a third set. Barty then took the next four games before Sharapova swung the momentum back in her favor. At 5-4 and serving for her fourth match point, Barty aced Sharapova to earn her first quarterfinal appearance in a Slam and the Barty Army fan club broke out in song.
"You gotta fight ... for your right ... to Bar-ty!"
At approximately that same moment, Tiafoe began fighting his way through a second-set tiebreaker -- which he won to go ahead two sets -- while former NCAA champion Danielle Collins was beginning a lopsided straight-sets upset of world No. 2 Angelique Kerber on Margaret Court Arena. With her win, Collins, 25, booked her first quarterfinal appearance at a Grand Slam. She'd previously never seen the second round at a major, but seemed utterly unsurprised by her success.
"I may not have won a Grand Slam match before this week," Collins said after her fourth-round win, "but I gotta tell you, I think it's gonna keep happening."
Collins, of course, was referring to her own Week 2 prospects, but she could have been predicting what would happen less than an hour later back on center court. Playing in the fourth round at a major for the first time in his life, Tiafoe closed out his upset of Dimitrov, then -- as the crowd sang "Happy Birthday" to him -- he was moved to tears in his on-court interview.
"It means the world. I worked my ass off, man," Tiafoe said. "I told my parents 10 years ago I was going to be a pro, I was going to change their lives and my life and now I'm in the quarters of a Slam. I can't believe it."
As he spoke, Tiafoe's quarterfinal opponent was being decided. World No. 2 Rafael Nadal was sprinting through a fourth-round defeat of Tomas Berdych. "He's gonna run me like crazy," Tiafoe said of the Spaniard. "I gotta go to sleep now to prepare."
On what became a standout day, it's tough to argue any player was under more pressure than Barty, 22, the only Australian player remaining in the tournament and a woman carrying the hopes of a country on her shoulders.
"She showed real heart out there today, and I'm so happy for her," said Australian Kimberly Birrell, who had her best Grand Slam showing this week and returned Sunday to support her fellow countrywoman. "So many people are watching and supporting her and that's how she looks at it. The support is overwhelming."
With each win, Barty's story is becoming a thing of legend around these parts. A top tennis prospect since she was barely out of diapers, Barty became burnt out and walked away from the sport in 2014 to play professional cricket for the Brisbane Heat. Two years later, she returned to the tour rejuvenated and with a new focus. In 2018 she won her first Grand Slam doubles title at the US Open with partner CoCo Vandeweghe. She also advanced to the fourth round in singles, her best performance at a major -- until Sunday.
"I needed to take that time away," said Barty, the first Australian woman to make the quarters at the Australian Open since Jelena Dokic in 2009. "I came back a better person on and off the court. I can go out there now and play an Ash Barty style of tennis and know no one else has that. I play with freedom and fun and try and create as much variety as possible. Every day, I try and challenge myself to add another string to my bow and become the complete player."
On Tuesday, she will also attempt to become the first Australian player to make the semifinals of a Grand Slam since 2005, when Lleyton Hewitt advanced to the Australian Open final and the semis at Wimbledon and the US Open.
"Sitting down with my team late last year, it was one of the goals we set out -- that we wanted to go deep into Slams," said Barty, who faces Kvitova in the next round. "I feel like that was the next step for me. It's amazing that it is happening in Australia in front of the best crowd in the world. There is absolutely nothing better."
Except maybe hoisting the Daphne Akhurst Memorial Cup in front of that crowd.