No.4 seed Amanda Anisimova is 1-0 against Zheng Saisai, having defeated the Chinese player 6-1, 6-1 in the second round of Hiroshima last year en route to her first WTA final. Anisimova is bidding to reach her first semifinal on American soil, while Zheng is going for her first semifinal at Premier level.
No.2 seed Aryna Sabalenka has won both of her previous encounters with No.6 seed Carla Suárez Navarro - both on hard courts last year, and both times going on to win the tournament. The Belarusian triumphed 6-1, 6-4 in the New Haven final and 7-6(2), 2-6, 6-2 in the first round of Wuhan en route to her biggest title to date.
No.1 seed Elina Svitolina takes on last year's runner-up Maria Sakkari in a reprise of their third-round encounter at Wimbledon one month ago, which Svitolina took 6-3, 6-7(1), 6-2 on her way to her maiden Grand Slam semifinal.
Qualifier Kristie Ahn scored her maiden Top 20 win over Elise Mertens yesterday to reach her second WTA quarterfinal following Nottingham 2017. The American is the first qualifier to reach the last eight of this tournament since Sachia Vickery in 2014 (when it was held in Stanford, Ahn's alma mater), and is bidding to become the first player to come through qualifying and make the last four since CoCo Vandeweghe reached the final as a lucky loser in 2012.
ORDER OF PLAY
STADIUM (starts 12 noon)
 Carla SUÁREZ NAVARRO (ESP) vs  Aryna SABALENKA (BLR)
 Elina SVITOLINA (UKR) vs  Maria SAKKARI (GRE)
Not before 4pm
 Donna VEKIC (CRO) vs [Q] Kristie AHN (USA)
Not before 7pm
 Amanda ANISIMOVA (USA) vs ZHENG Saisai (CHN)
Monique ADAMCZAK (AUS) / Storm SANDERS (AUS) vs  Desirae KRAWCZYK (USA) / Alicja ROSOLSKA (POL)
COURT 1 (starts 5.30pm)
Shuko AOYAMA (JPN) / Ena SHIBAHARA (JPN) vs  Lyudmyla KICHENOK (UKR) / Nadiia KICHENOK (UKR)