Comeback stars Ajla Tomljanovic and Daria Saville have roared into the US Open second round to set up a pair of show-court show-stoppers in New York.
Playing her first match of the year after undergoing knee surgery in January, Tomljanovic shook off some rust in an emotion-charged 3-6 6-2 6-4 win over dogged Hungarian baseliner Panna Udvardy.
Tomljanovic looked in a state of disbelief after clinching victory, shaking her head and repeatedly asking her courtside entourage "how, how, how?"
"In a way I feel like I have no business being in the second round. This was just a huge test for me," she said.
"I know it might sound weird but I played the best I could - or more. I did more than I thought I could and barely got over the line. That tells you something.
"I tapped into my competitiveness, that felt like it was all heart, but I wish it felt better physically than it did."
The win earned the 2022 quarter-finalist an exciting rematch with fourth-seeded Australian Open runner-up Elena Rybakina on Thursday (AEST).
Rybakina denied Tomljanovic in a pulsating three-set Wimbledon quarter-final last year before going on to claim her maiden grand slam trophy at the All England Club.
The Kazakh has kicked on in 2023 to emerge as one of the dominant forces in women's tennis.
For Tomljanovic, it's been a season of despair until Monday.
On the cusp of being seeded for the first time at a grand slam, the 29-year-old was forced to withdraw from her home major on the eve of the tournament.
She also sat out the French Open and Wimbledon and watched her ranking tumble to No.127 in the world.
"I'm on a high emotionally but I am very realistic about where my knee and body is at," Tomljanovic said.
"I am very realistic that I still need time, but I would be stupid to be complaining being here in the second round. It just felt like that reward after so many months of just torture."
Saville is also in the infancy of her return from a torn ACL but made a flying start to her Open campaign to set up a second-round clash with world No.1 and defending champion Iga Swiatek.
Saville looked anything but a player on the comeback trail from a serious knee injury as she routed American teenager Clervie Ngounoue 6-0 6-2 in little more than an hour.
"I was very composed," Saville said after notching her first win at Flushing Meadows in five years.
Rinky Hijikata also progressed in vastly different fashion on a promising opening day for the Australian contingent.
Hijikata vindicated his wildcard entry with a 7-5 5-7 6-3 7-5 victory over Russian Pavel Kotov in a sapping contest stretching a minute shy of four hours.
The hard-earned victory was the 22-year-old's first at a grand slam outside of Australia.
While Tomljanovic, Saville and Hijikata rolled on, fellow Australians Alexei Popyrin, Kim Birrell, Olivia Gadecki and wildcard Storm Hunter all bowed out in the first round.
Birrell, a qualifying lucky loser, battled hard in a 6-3 7-6 (7-4) loss to 2021 Australian Open finalist Jennifer Brady, while Hunter succumbed 6-4 6-0 to Czech 10th seed Karolina Muchova, the 2023 French Open runner-up.
Gadecki let a set-and-a-break lead slip in a dispiriting 1-6 6-3 6-4 loss to 16-year-old Russian Mirra Andreeva and Popyrin crashed to a 6-3 6-4 3-6 6-3 defeat to Swiss qualifier Dominic Stricker.
World No.13 Alex de Minaur, along with Max Purcell, Chris O'Connell, Aleksandar Vukic, Jordan Thompson, Thanasi Kokkinakis, Jason Kubler and qualifying lucky loser James Duckworth all play first-round matches on day two.