Victoria Azarenka notched up her third Top 30 win since Miami last year over No.2 seed Danielle Collins in the first round, and will now bid to win consecutive matches for the first time this year in the Belarusian's first encounter with Tatjana Maria.
Qualifier Beatriz Haddad Maia is bidding to make her first WTA quarterfinal since her run to the Seoul final in 2017. The Brazilian, who is making her comeback from a back injury last year, is also looking for a maiden Top 10 win against Sloane Stephens; in six previous matches against opposition in that stratum, Haddad Maia has won one set - against Jelena Ostapenko in the Seoul final.
No.4 seed Mihaela Buzarnescu snapped her 11-match losing streak yesterday, and is 1-0 against Bianca Andreescu, having defeated the Canadian 6-0, 6-2 in the first round of the ITF W50 event in Toronto in 2015.
For the second consecutive round, No.3 seed Donna Vekic faces an opponent against whom she has a 0-1 record, with that previous match taking place in Madrid. Having dispatched Misaki Doi in the first round, the Croat will be hoping to avenge her 6-3, 6-2 qualifying loss in 2015 to Christina McHale.
No.7 seed Zheng Saisai defeated Timea Babos 7-5, 6-4 in their only previous meeting, in the first round of Tianjin in 2014 - a win that paved the way to the Chinese player's maiden WTA semifinal.
ORDER OF PLAY (all courts start 4pm)
Sloane STEPHENS (USA)  vs [Q] Beatriz HADDAD MAIA (BRA)
GRAND STAND CALIENTE
After 1 ATP match
Tatjana MARIA (GER) vs [WC] Victoria AZARENKA (BLR)
ZHENG Saisai (CHN)  vs Timea BABOS (HUN)
WANG Yafan (CHN) vs Monica PUIG (PUR)
Sofia KENIN (USA)  vs Katie BOULTER (GBR)
Donna VEKIC (CRO)  vs [Q] Christina MCHALE (USA)
[Q] Varvara FLINK (RUS) vs Johanna KONTA (GBR) 
Desirae KRAWCZYK (USA) / Giuliana OLMOS (MEX)  vs Ysaline BONAVENTURE (BEL) / Kaitlyn CHRISTIAN (USA)
Johanna KONTA (GBR) / Laura SIEGEMUND (GER) vs Victoria AZARENKA (BLR) / ZHENG Saisai (CHN)
Paula KANIA (POL) / Yana SIZIKOVA (RUS) vs Dalila JAKUPOVIC (SLO) / Irina KHROMACHEVA (RUS) 
Not before 5.30pm
Bianca ANDREESCU (CAN) vs Mihaela BUZARNESCU (ROU) 
After 1 ATP match
Irina BARA (ROU) / Mihaela BUZARNESCU (ROU)  vs Tatjana MARIA (GER) / Christina MCHALE (USA)