Petra Kvitova (CZE) vs. [WC] Caroline Wozniacki (DEN)
Mirra Andreeva vs.  Coco Gauff (USA)
Two generational rivalries highlight Day 3's order of play at the US Open. One pits two old foes against each other for the 15th time in 14 years; the other is the second meeting this season between two of the best teenagers in the world, a nascent head-to-head that nonetheless has era-defining potential.
Petra Kvitova and Caroline Wozniacki are both 33-year-old Grand Slam champions, but they've taken contrasting routes to this year's US Open. Kvitova has shown resurgent form this year to win titles in Miami and Berlin, and to return to the Top 10 for the first time since 2021 (she is presently just outside it at No.11).
But consistency has never been the Czech's forte, and she suffered early exits in Montreal (to Belinda Bencic in the third round) and Cincinnati (to Linda Noskova in the second round). And she has struggled to take her best form into majors in recent years: the last time she went beyond the fourth round of a Slam was at Roland Garros 2020. New York has rarely been her happiest hunting ground, either. Kvitova's career-best performances here are a pair of quarterfinal runs in 2015 and 2017.
By contrast, Wozniacki is a two-time finalist here, and it was entirely fitting that the US Open should be the Dane's first Grand Slam of her surprise return from maternity leave. Just three tournaments into her comeback, the jury is still out on how far Wozniacki can go. She has displayed vintage form in a pair of wins, defeating Kimberly Birrell in Montreal and qualifier Tatiana Prozorova in the first round here on Monday. But she has lost both of her matches against Top 100 opposition -- Marketa Vondrousova in Montreal and Varvara Gracheva in Cincinnati -- in straight sets.
Facing someone with whom she's shared so much history could ignite Wozniacki's comeback, though. The pair last played in 2018, when they split two three-set barnburners -- Kvitova winning 3-6, 7-6(3), 7-5 in Doha and Wozniacki reversing the result 7-5, 3-6, 6-2 at the WTA Finals Singapore. Overall, Kvitova leads the head-to-head 8-6, including 6-2 on outdoor hard courts and four of their last five matches.
Kvitova and Wozniacki both made their US Open debuts as 17-year-olds in 2007, with Kvitova making the second qualifying round and Wozniacki the second round of the main draw. Coco Gauff was 3 years old at the time, and Mirra Andreeva just 4 months old.
This year Gauff, 19, and Andreeva, 16, have been making a strong case that their rivalry could be as key to the next decade as Kvitova and Wozniacki were to the 2010s. Andreeva has established herself on the main tour in ominously quick time, rocketing from No.312 to her present No.63 in just four months. She reached the third round of Roland Garros on her Grand Slam debut, and went one better to the last 16 at Wimbledon. The US Open is just her seventh tour-level main draw, and her 1-6, 6-3, 6-4 defeat of qualifier Olivia Gadecki marked her sixth first-round win at this level.
Andreeva's arrival entails a new dynamic for Gauff, who won their only previous meeting 6-7(5), 6-1, 6-1 in the third round of Roland Garros. The American had been comfortably the youngest player in the Top 100 for three years between 2019 and 2022, but now finds herself needing to use her superior experience against hungry youngsters. Not that she focuses too much on age.
"I never thought about it before when I was on the younger end, and I never thought about it in the past when I was on the older end," Gauff said after her 3-6, 6-2, 6-4 first-round win over Laura Siegemund. "It means nothing ... I think the media, in general, put too much on age. It doesn't matter if I'm playing someone younger. Sidn't matter when I was younger, I was still beating some people older than me. She has an equal opportunity to do that on Wednesday."
Three more to watch
 Victoria Azarenka vs. Zhu Lin (CHN)
Three-time US Open finalist Azarenka takes on one of the most improved players of 2023. This year has seen Zhu, 29, defeat a Top 10 player for the first time (Maria Sakkari) to make her Grand Slam second-week debut at the Australian Open; capture her maiden Hologic WTA Tour title in Hua Hin; and crack the Top 50 for the first time, hitting a career high of No.33 in March. Zhu arrives at the US Open fresh off a run to the Cleveland semifinals that included a second Top 10 victory over Caroline Garcia.
Azarenka just about held Zhu off 4-6, 6-1, 6-4 in the fourth round of the Australian Open, one of the best matches of that tournament. The 34-year-old has not won consecutive matches in any of her events since Wimbledon, but was impressive in a 6-1, 6-2 first-round rout of wild card Fiona Ferro. Can she survive Zhu again?
 Iga Swiatek (POL) vs Daria Saville (AUS)
Swiatek and Saville dropped three games combined in their first-round defeats of Rebecca Peterson and Clervie Ngounoue respectively. Dominant scorelines are nothing new for Swiatek, but for Saville -- who only returned to action in June following nine months sidelined by an ACL injury -- her high level was a meaningful reminder of her top form.
"I think I can still make her life very uncomfortable," Saville said after her win. A former World No.20 who owns 13 career Top 10 wins, the 29-year-old has long delighted in gritting out upsets of taller, stronger opponents. Though Swiatek won their only previous meeting 6-3, 6-3 in the first round of Adelaide 2022, the World No.1 will have to be wary.
 Elena Rybakina (KAZ) vs. Ajla Tomljanovic (AUS)
Twelve months ago, the US Open was the site of Tomljanovic's greatest career moment as she ended Serena Williams's career en route to the quarterfinals. This year, it's her first tournament back after nine months spent recovering from a knee injury.
Tomljanovic made a winning return, battling past Panna Udvardy 3-6, 6-2, 6-4, but Rybakina will be a much tougher proposition. The Kazakh was dealt one of the toughest unseeded players in the draw in her opener, but brushed Marta Kostyuk -- an opponent she hhad never beaten before -- aside 6-2, 6-1. Rybakina has won both of her encounters with Tomljanovic, including a 4-6, 6-2, 6-3 win in the 2022 Wimbledon quarterfinals en route to her first major crown.
Also in action
Yet another comeback story could unfold as 2021 Australian Open finalist Jennifer Brady takes on this year's Australian Open semifinalist Magda Linette. Brady is playing her fifth tournament after being sidelined for nearly two years by plantar fasciitis, and leads her overall head-to-head 3-1 against the No.24 seed.
2022 Australian Open finalist Danielle Collins also takes a 3-1 record into her tie with No.32 seed Elise Mertens, who needed to escape from triple match point down against qualifier Mirjam Bjorklund in the first round.
No.19 seed Beatriz Haddad Maia won one of the best matches of the first round 6-2, 5-7, 6-4 over 2017 champion Sloane Stephens, and faces another dangerous home player in Taylor Townsend. In their only previous meeting, Townsend won 6-1, 6-4 in 2019 Miami qualifying.
Roland Garros and Cincinnati finalist Karolina Muchova was the first player into Round 2 after dismissing wild card Storm Hunter in just 65 minutes. The Czech No.10 seed faces Magdalena Frech, whom she defeated 6-2, 6-2 in last year's Billie Jean King Cup Finals.