Petra Kvitova's second round against Alizé Cornet is a rematch of their 2012 encounter at the same stage of the US Open - the only time they have played each other. The Czech won it 6-4, 6-3 en route to the fourth round - one of her four second week showings in Flushing Meadows, the only Slam at which she has never reached the semifinals.
No.5 seed Caroline Wozniacki is unbeaten in seven meetings over nine years against her opponent today, Ekaterina Makarova. The Dane has dropped just two sets overall - in the 2012 Seoul semifinals and the 2013 Eastbourne quarterfinals - and won their most recent encounter, in the first round of Madrid in 2014, 6-2, 6-2.
Makarova, a former World No.8 and a 2014 US Open semifinalist, has been rounding back into form this summer after falling out of the Top 50 in July. The Russian captured her third career title in Washington DC four weeks ago, and followed it up by scoring wins over Johanna Konta (in Toronto) and Angelique Kerber (in Cincinnati) - bringing her record against Top 5 opposition in 2017 to an impressive 5-0. Makarova is also tied with Svetlana Kuznetsova for the fourth highest number of Top 10 wins at Slams among active players, with 10 in total (behind only Serena Williams, Venus Williams and Maria Sharapova).
Wimbledon victor Garbiñe Muguruza is the only reigning Slam champion to hold multiple titles over the past 12 months. will bid to make the third round at Flushing Meadows for the first time in her career today. Despite her relatively poor record here, every player who has beaten the Spaniard in New York has a career high ranking in the Top 20: Muguruza lost her opening match in her 2012 debut to Sara Errani, and fell at the first hurdle again in 2014 to Mirjana Lucic-Baroni. In 2015 and 2016, she was stopped in the second round by Johanna Konta and Anastasija Sevastova respectively.
Americans Sachia Vickery and Sofia Kenin will play for what would be a maiden Slam third round spot for either. Qualifier Vickery's first-round win over Natalia Vikhlyantseva was her first Slam win since her debut here in 2013, when she received a wildcard after winning the USTA U18 National Championships. Kenin, meanwhile, is a wildcard entry here for the third consecutive year - and her upset of No.32 seed Lauren Davis in the first round was her own first Slam win.
Carla Suárez Navarro takes on Mirjana Lucic-Baroni for the fourth time today, having won all three of their previous encounters - including two weeks ago in the first round of Cincinnati 6-3, 7-5.
This time last year, Ashleigh Barty was ranked No.304, just three tournaments into a comeback after a two-year hiatus from tennis. Still only 21 years old, she's now ranked No.43 having notched up her maiden title (in Kuala Lumpur), a debut Premier final (in Birmingham) and three Top 20 scalps (Garbiñe Muguruza in Birmingham, Elena Vesnina in Toronto and Venus Williams in Cincinnati) in 2017. On Monday, the Australian faced a seed in the first round of a Slam for the third straight time - but this time came away with the win over No.21 Ana Konjuh.
Both of No.18 seed Caroline Garcia's previous encounters with her second-round opponent, Ekaterina Alexandrova, were at the Limoges WTA 125K event. In 2015, the Frenchwoman scraped through a three-setter 1-6, 6-2, 7-5 - but the following year, the Russian exacted her revenge in the tournament final 6-4, 6-0.
Venus Williams's first-round win over Viktoria Kuzmova preserved the American's record of zero first round losses at the US Open. In 18 previous appearances, she has only lost in the second round twice, in 2012 (to Angelique Kerber) and 2013 (to Zheng Jie). In 2011, the year Williams was diagnosed with Sjögren's syndrome, she withdrew before her second round match against Sabine Lisicki.
Océane Dodin, Williams's opponent today, is 0-4 in Slam second-round matches. Only five active players have more defeats and no wins at this stage: Lara Arruabarrena (0-5), Chang Kai-Chen (0-5), Aliaksandra Sasnovich (0-5), Wang Qiang (0-6) and Urszula Radwanska (0-9).
Maria Sharapova, who faces Timea Babos today, has not lost in the second round of the US Open since her 2003 debut, when she was felled 6-3, 6-4 by Émilie Loit. Her most recent defeat at this stage of any Slam was at Wimbledon 2013, when her conqueror was Michelle Larcher de Brito.
Just seven matches were completed in a washed-out Tuesday - but one of them was the shock of the tournament so far. Peter Bodo analyses the fall of Angelique Kerber and the redemption of Naomi Osaka for ESPN.
Sofia Kenin got a special reward after winning her first Slam match on Monday. The Moscow-born American tells Nina Pantic at Tennis.com more about it - and her journey so far.
On Monday, Arina Rodionova won her first ever US Open main draw match. The outspoken Australian has long had a voice off court - she talks to WTA Insider about defending her friend Casey Dellacqua, taking on Twitter trolls and working towards a degree while on tour.
Relive the highlights of Naomi Osaka's stunning upset of defending champion Angelique Kerber - and get to know more about the Japanese 19-year-old.