In No.1 seed Simona Halep's only previous meeting with wildcard Barbora Krejcikova in the first round of Bucharest 2016, the Romanian was stunned by the then World No.200 for a set before recovering to win 3-6, 6-1, 6-1 and going on to lift her 13th trophy. Both players would go on to multiple Grand Slam titles and the World No.1 ranking - Halep in singles and Krejcikova in doubles. The Czech is yet to defeat a Top 30 player in singles.
Tamara Zidansek, fresh off the Palermo doubles title last week with Arantxa Rus, faces a rematch of a 2019 marathon against wildcard Eugenie Bouchard today. Their only past encounter found the Slovenian needing two hours and 20 minutes to triumph 6-3, 5-7, 8-6 in the first round of Wimbledon for a memorable main draw debut at The Championships.
Sara Sorribes Tormo and Laura Siegemund have played once before, with Sorribes Tormo needing only 72 minutes to dispatch the German 6-1, 6-0 in last year's Bol 125K quarterfinals and going on to reach the biggest final of her career to date.
Hua Hin finalist Leonie Kung is bidding to reach the second WTA quarterfinal of her career in just her third main draw. The Swiss player has entered each of those in different ways: as a wildcard, fresh off the Wimbledon junior final, at Gstaad 2018; as a qualifier in Hua Hin this February; and as a lucky loser this week, having fallen to Mayar Sherif in qualifying.
Another lucky loser, Magdalena Frech, is seeking to reach her maiden WTA quarterfinal, having won her first main draw match since 2018 this week and just her fourth overall. The Pole's only previous meeting with Monterrey semifinalist Arantxa Rus was in Wimbledon qualifying last year, with Rus winning 6-4, 6-2.
ORDER OF PLAY (all courts start 11am)
[WC] Eugenie BOUCHARD (CAN) vs Tamara ZIDANSEK (SLO)
[LL] Magdalena FRECH (POL) vs Arantxa RUS (NED)
 Simona HALEP (ROU) vs [WC] Barbora KREJCIKOVA (CZE)
Irina-Camelia BEGU (ROU) vs [LL] Leonie KUNG (SUI)
Cornelia LISTER (SWE) / Renata VORACOVA (CZE) vs  Lucie HRADECKA (CZE) / Kristyna PLISKOVA (CZE)
Not before 12 noon
Laura SIEGEMUND (GER) vs Sara SORRIBES TORMO (ESP)
 Monica NICULESCU (ROU) / Raluca OLARU (ROU) vs Lidziya MAROZAVA (BLR) / Yana SIZIKOVA (RUS)
Rosalie VAN DER HOEK (NED) / Yanina WICKMAYER (BEL) vs Arantxa RUS (NED) / Tamara ZIDANSEK (SLO)
 Barbora KREJCIKOVA (CZE) / Katerina SINIAKOVA (CZE) vs Veronika KUDERMETOVA (RUS) / Anastasia PAVLYUCHENKOVA (RUS)