2013 champion Victoria Azarenka is the only former Cincinnati winner remaining in the draw following the third-round defeats of Serena Williams and Vera Zvonareva. The Belarusian former World No.1, who faces Ons Jabeur for the first time, is in her first Premier 5 quarterfinal since Rome 2019 and is aiming to make her second semifinal at this level or above since returning from maternity leave, having previously reached the last four at Miami 2018.
Ons Jabeur's breakthrough into the Top 50 in the world has seen the Tunisian reach the two biggest quarterfinals of her career at the Australian Open and in Doha this year. However, she is 0-3 in this round in 2020, having also lost in the last eight of Lexington; a win over Victoria Azarenka to snap that streak would put the 25-year-old into the biggest semifinal of her career, and first since Tianjin last October.
No.8 seed Johanna Konta will face No.13 seed Maria Sakkari for the fourth time, but first on hard courts. Previously, the Briton had taken both of their grass meetings - winning 6-4, 6-1 in the third round of Wimbledon 2017 and 6-4, 7-6(4) in the second round of Eastbourne 2019 - while Sakkari had triumphed in their only clay encounter, capturing her maiden title 2-6 6-4, 6-1 in the 2019 Rabat final.
No.4 seed Naomi Osaka is 3-0 against No.12 seed Anett Kontaveit, having first defeated the Estonian in the 2015 Surbiton ITF $50K semifinals on grass, then twice at WTA level on hard courts in the first round of the 2016 Japan Women's Open and the second round of Dubai 2018. The only one of those matches to go to three sets was the Surbiton clash, which Osaka took 6-4, 6-7(5), 6-2 to reach her only grass-court final at any level to date. Kontaveit is bidding for her third Top 10 win of the season after beating Belinda Bencic at the Australian Open and Elina Svitolina in Fed Cup zonal action, and 12th overall.
No.12 seed Anett Kontaveit and No.14 seed Elise Mertens have both sustained strong form from restarting their seasons on European clay this month: Kontaveit was runner-up in Palermo to Fiona Ferro and is now 7-1 since the Tour resumption, while Mertens was runner-up in Prague to Simona Halep and is 7-2.
American Jessica Pegula is the last home player remaining, and the fourth qualifier to reach the Cincinnati quarterfinals since it became a Premier 5 event in 2009, following Akgul Amanmuradova in 2010, Anna Karolina Schmiedlova in 2015 and Timea Babos in 2016. The last qualifier to reach the Cincinnati semifinals was also Amanmuradova in 2007, when it was stil a Tier III tournament.
ORDER OF PLAY (all courts start 11am)
 Elise MERTENS (BEL) vs [Q] Jessica PEGULA (USA)
After 2 ATP matches, not before 5pm
 Johanna KONTA (GBR) vs  Maria SAKKARI (GRE)
Not before 1pm
[4/WC] Naomi OSAKA (JPN) vs  Anett KONTAVEIT (EST)
Ons JABEUR (TUN) vs Victoria AZARENKA (BLR)
 Kveta PESCHKE (CZE) / Demi SCHUURS (NED) vs Ellen PEREZ (AUS) / Storm SANDERS (AUS)
Not before 1pm
Anna BLINKOVA (RUS) / Veronika KUDERMETOVA (RUS) vs  Nicole MELICHAR (USA) / XU Yifan (CHN)
Not before 2.30pm
[WC] Jessica PEGULA (USA) / Shelby ROGERS (USA) vs Viktoria KUZMOVA (SVK) / Iga SWIATEK (POL)
 Elise MERTENS (BEL) / Aryna SABALENKA (BLR) vs  Lucie HRADECKA (CZE) / Andreja KLEPAC (SLO)