CANCHA CENTRAL -- 11:00 a.m. start
 Kristina MLADENOVIC (FRA) vs. [LL] Greta ARN (HUN)
Following 1 ATP match, not before 3:00 p.m.
Margarita GASPARYAN (RUS) vs.  Garbiñe MUGURUZA (ESP)
Zarina DIYAS (KAZ) vs.  Victoria AZARENKA (BLR)
Not before 7:00 p.m.
 Angelique KERBER (GER) vs. Karolina MUCHOVA (CZE)
CANCHA 1 -- 11:00 a.m. start
Following 3 ATP matches
 Asia MUHAMMAD (USA) / Maria SANCHEZ (USA) vs. Giuliana OLMOS (MEX) / Luisa STEFANI (BRA)
CANCHA 4 -- 11:00 a.m. start
Following 2 ATP matches
Harriet DART (GBR) / Valeria SAVINYKH (RUS) vs. Monique ADAMCZAK (AUS) / Jessica MOORE (AUS)
Alternates vs. Sharon FICHMAN (CAN) / Erin ROUTLIFFE (NZL)
Defending champion Garbiñe Muguruza defeated 2012 champion Timea Babos to win the Abierto GNP Seguros last year -- which was Muguruza's only title of 2018. Muguruza will face Margarita Gasparyan in the second round, in the first meeting between the two players.
Top seed and reigning Wimbledon champion Angelique Kerber has made the Monterrey final in her last two appearances at the event, in 2013 and 2017. In both instances, she lost the championship match to Anastasia Pavlyuchenkova.
Kerber will face Karolina Muchova for the second time in less than a month. Kerber had to come back from a set down to beat Muchova at the Miami Open, in the most recent event for both players.
Victoria Azarenka has a 1-0 head-to-head lead on Zarina Diyas, winning their match en route to her Indian Wells title in 2016. Diyas did receive a walkover from Azarenka at Birmingham in 2015.
Azarenka won her first-ever match at Monterrey on Tuesday with a straight-set victory over qualifier Miyu Kato.