Two-time champion Petra Kvitova, who lifted the Wuhan trophy in 2014 and 2016, faces Polona Hercog for the first time in seven years in one of two second-round matches on the schedule. Kvitova, who has won only one match since Wimbledon following a forearm injury, won their only prior match 7-6(6), 6-1 in the first round of the 2012 US Open.
No.11 seed Angelique Kerber leads the head-to-head against Monica Puig 3-2, with the two players having alternated victories in their last four matches. Kerber won their first meeting, a second-round 3-6, 6-4, 7-6(7) thriller in Brisbane in 2013, as well as taking straight-sets wins in the second round of Toronto 2015 and the third round of Dubai 2017; Puig was triumphant in their most high-profile clash, taking gold 6-4, 4-6, 6-1 in the 2016 Rio de Janeiro Olympic Games final, as well as their most recent match, 6-3, 6-4 in the first round of Luxembourg 2017.
No.16 seed Donna Vekic is yet to drop a set to Victoria Azarenka in two previous meetings, both during this year's American hardcourt swing - 6-4, 6-3 in the second round of San Jose and 6-2, 7-5 in the second round of Cincinnati.
No.9 seed Aryna Sabalenka continues her title defence against Danielle Collins - whom she defeated 6-0, 4-6, 6-4 in their only prior clash, in the first round of the US Open last year.
Elise Mertens and Katerina Siniakova will meet for the third time - once again in an opening round this year. Mertens was the victor on both previous occasions, 7-6(4), 2-6, 6-2 in Sydney and 6-4, 6-2 in Doha en route to lifting her first Premier trophy.
Petra Martic has been something of a nemesis for Kristina Mladenovic, particularly over the course of 2019. The Croat leads the overall head-to-head 4-1, with Mladenovic's only win coming via retirement six years ago; so far this year, Martic has defeated the Frenchwoman 7-6(4), 4-6, 7-6(2) in the Istanbul quarterfinals - at three hours and 17 minutes, the fifth-longest match of the season to date - and followed it up with two rather more straightforward wins, 6-2, 6-1 in the second round of Roland Garros and 6-0, 6-3 in the Zhengzhou semifinals two weeks ago.
No.13 seed Caroline Wozniacki had never lost to Hsieh Su-Wei in four meetings between 2008 and 2015 - until the fourth round of Miami this year, when the Chinese Taipei player finally captured her first win in the series 6-4, 6-7(0), 6-2. The only set Hsieh had won from Wozniacki prior to that was in the second round of Beijing 2012 en route to a 6-7(5), 7-6(3), 6-0 loss.
No.12 seed Madison Keys leads the head-to-head against Camila Giorgi 4-2, including 2-0 on outdoor hard courts - their first meeting, 3-6, 6-4, 6-4 in the quarterfinals of the 2012 ITF 50K event in New Braunfels, and their most recent, 6-2, 6-2 in the second round of Cincinnati last year. The Italian's only two wins over Keys came on indoor hard courts (6-2, 6-1 in a Fed Cup first-round rubber in 2014) and grass (6-4, 6-7(10), 6-1 in the second round of Wimbledon 2017).
2015 runner-up Garbiñe Muguruza has beaten wildcard Peng Shuai both times they have previously played, 6-2, 3-6, 6-3 in the second round of New Haven 2014 and 6-4, 6-2 in the first round of Madrid 2018. Muguruza is bidding to snap a five-match losing streak dating back to the fourth round of Roland Garros this year; Peng has won just one match in three prior appearances in Wuhan, a 2011 first-round upset of Petra Kvitova.
2016 semifinalist Svetlana Kuznetsova lost to Yulia Putintseva in their first meeting 6-3, 6-7(4), 7-5 in the 2017 St Petersburg quarterfinals - but has not dropped a set to the Kazakh since, winning 6-3, 6-4 in the second round of Cincinnati 2017 and 6-2, 6-2 in the 2018 Washington quarterfinals.
Qualifier Christina McHale defeated No.14 seed Anastasija Sevastova 6-0, 5-7, 7-6(2) in their sole previous encounter in the first round of Nottingham 2017. The American is bidding for her first Top 20 scalp since Beijing 2017, where she upset Sloane Stephens in the first round.
No.15 seed Sofia Kenin and Anastasia Pavlyuchenkova will meet for the first time, with both coming off stellar starts to the Asian swing: Kenin took her third career title last week in Guangzhou, while Pavlyuchenkova reached her first Premier-level final in two years in Osaka, coming runner-up to Naomi Osaka.
Czech compatriots Marie Bouzkova and Karolina Muchova have split two previous meetings, with Bouzkova winning 6-0, 7-6(4) in the semifinals of an ITF 10K in Poertschach in 2015 and Muchova gaining revenge 6-4, 6-3 in Miami qualifying this March.
ORDER OF PLAY (all courts start 11am)
Victoria AZARENKA (BLR) vs  Donna VEKIC (CRO)
 Caroline WOZNIACKI (DEN) vs HSIEH Su-Wei (TPE)
Monica PUIG (PUR) vs  Angelique KERBER (GER)
[WC] PENG Shuai (CHN) vs Garbiñe MUGURUZA (ESP)
Not before 7pm
 Petra KVITOVA (CZE) vs Polona HERCOG (SLO)
 Aryna SABALENKA (BLR) vs Danielle COLLINS (USA)
[Q] Svetlana KUZNETSOVA (RUS) vs Yulia PUTINTSEVA (KAZ)
WANG Yafan (CHN) vs [Q] Lauren DAVIS (USA)
[WC] Samantha STOSUR (AUS) vs Amanda ANISIMOVA (USA)
Katerina SINIAKOVA (CZE) vs Elise MERTENS (BEL)
Not before 5pm
Anastasia PAVLYUCHENKOVA (RUS) vs  Sofia KENIN (USA)
Not before 7pm
Marie BOUZKOVA (CZE) vs Karolina MUCHOVA (CZE)
 Anastasija SEVASTOVA (LAT) vs [Q] Christina MCHALE (USA)
Petra MARTIC (CRO) vs Kristina MLADENOVIC (FRA)
 Madison KEYS (USA) vs Camila GIORGI (ITA)
Makoto NINOMIYA (JPN) / YANG Zhaoxuan (CHN) vs Shuko AOYAMA (JPN) / Ena SHIBAHARA (JPN)
Anna BLINKOVA (CZE) / Renata VORACOVA (CZE) vs Kaitlyn CHRISTIAN (USA) / Jessica MOORE (AUS)
Not before 5pm
Storm SANDERS (AUS) / Dayana YASTREMSKA (UKR) vs  Nicole MELICHAR (USA) / Kveta PESCHKE (CZE)
[Q] Kateryna KOZLOVA (UKR) vs Alison RISKE (USA)
[Q] Veronika KUDERMETOVA (RUS) vs Ekaterina ALEXANDROVA (RUS)
[WC] Caroline GARCIA (FRA) / Bethanie MATTEK-SANDS (USA) vs Darija JURAK (CRO) / María José MARTÍNEZ SÁNCHEZ (ESP)
Oksana KALASHNIKOVA (GEO) / Vania KING (USA) vs Monique ADAMCZAK (AUS) / HAN Xinyun (CHN)
[WC] Kiki BERTENS (NED) / Lesley PATTINAMA KERKHOVE (NED) vs  DUAN Yingying (CHN) / Veronika KUDERMETOVA (RUS)