No.5 seed and 2019 semifinalist Elina Svitolina opens her campaign against 18-year-old Roland Garros semifinalist Amanda Anisimova, whom she previously defeated 6-4, 6-4 in the third round of Cincinnati 2018.
2016 champion Carla Suárez Navarro owns a 3-0 head-to-head lead over Zhang Shuai, having defeated the Chinese player twice in the first round of Wimbledon in 2014 and 2016 - the second of which was the only match to go to three sets - and once previously in the Middle East, 6-4, 6-4 in the second round of Dubai last year.
2011 champion Vera Zvonareva reprises her 2018 qualifying tilt here against Hsieh Su-Wei - the pair's only previous encounter, won by Zvonareva 6-4, 6-4.
No.10 seed Petra Martic and Barbora Strycova square off in a first-round tilt for the second time in as many weeks. Martic won their Dubai opener 6-3, 6-3 a week ago to extend her winning streaks against the Czech to four matches (out of five total) and eight sets.
No.17 seed Donna Vekic faces a rematch of her Australian Open third round encounter with 18-year-old Iga Swiatek today - which the Polish teenager won 7-5, 6-3 en route to making the second week for the second time in her first five Grand Slams.
This time last year, Alison Riske and Jennifer Brady squared off in qualifying - but now the all-American derby finds Riske as the No.13 seed and Brady coming off the biggest semifinal of her career in Dubai last week. Riske was a 6-2, 6-4 winner 12 months ago, but Brady would get revenge 6-3, 7-6(4) in the third round of the Indian Wells 125K event to level the head-to-head at 1-1.
Anastasia Pavlyuchenkova has beaten Yulia Putintseva twice in two previous meetings, both in 2016, winning 7-5, 6-1 in the second round of Wimbledon and 6-4, 1-6, 7-5 - saving one match point - in the first round of Montréal.
Qualifier Kirsten Flipkens will seek to repeat her 6-3, 3-6, 6-3 upset of 19-year-old Dayana Yastremska in the second round of Moscow in October, the pair's sole previous encounter.
Qualifier Tereza Martincova and lucky loser Misaki Doi will face each other for the second time in this tournament: Martincova booked her spot in the first Premier 5 main draw of her career with a 7-5, 6-1 defeat of Doi in the final round of qualifying before Simona Halep's withdrawal opened up a spot for the Japanese player as well.
CENTRE COURT (starts not before 3.30pm)
 Maria SAKKARI (GRE) vs Julia GOERGES (GER)
 Kiki BERTENS (NED) vs Karolina MUCHOVA (CZE)
Not before 7pm
 Elina SVITOLINA (UKR) vs Amanda ANISIMOVA (USA)
[WC] Sorana CIRSTEA (ROU) vs  Elena RYBAKINA (KAZ)
COURT 1 (starts 2pm)
ZHANG Shuai (CHN) vs Carla SUÁREZ NAVARRO (ESP)
 Petra MARTIC (CRO) vs Barbora STRYCOVA (CZE)
Iga SWIATEK (POL) vs  Donna VEKIC (CRO)
Jennifer BRADY (USA) vs  Alison RISKE (USA)
Darija JURAK (CRO) / Yaroslava SHVEDOVA (KAZ) vs Ekaterina ALEXANDROVA (RUS) / Anna BLINKOVA (RUS)
COURT 2 (starts 3.30pm)
Anett KONTAVEIT (EST) vs Anastasija SEVASTOVA (LAT)
Anastasia PAVLYUCHENKOVA (RUS) vs Yulia PUTINTSEVA (KAZ)
Dayana YASTREMSKA (UKR) vs [Q] Kirsten FLIPKENS (BEL)
HAN Xinyun (CHN) / PENG Shuai (CHN) vs Magda LINETTE (POL) / Patricia Maria TIG (ROU)
COURT 3 (starts 3.30pm)
ZHENG Saisai (CHN) vs  Marketa VONDROUSOVA (CZE)
HSIEH Su-Wei (TPE) vs [WC] Vera ZVONAREVA (RUS)
Lucie HRADECKA (CZE) / Andreja KLEPAC (SLO) vs ZHANG Shuai (CHN) / ZHENG Saisai (CHN)
DUAN Yingying (CHN) / Veronika KUDERMETOVA (RUS) vs [WC] Alla KUDRYAVTSEVA (RUS) / Katarina SREBOTNIK (SLO)
COURT 5 (starts 3.30pm)
[LL] Misaki DOI (JPN) vs [Q] Tereza MARTINCOVA (CZE)
Belinda BENCIC (SUI) / Sofia KENIN (USA) vs  Ashleigh BARTY (AUS) / Demi SCHUURS (NED)
[WC] Cagla BUYUKAKCAY (TUR) / Laura SIEGEMUND (GER) vs [WC] Caroline GARCIA (FRA) / Sania MIRZA (IND)
 Gabriela DABROWSKI (CAN) / Jelena OSTAPENKO (LAT) vs Kaitlyn CHRISTIAN (USA) / Oksana KALASHNIKOVA (GEO)
 Barbora KREJCIKOVA (CZE) / Katerina SINIAKOVA (CZE) vs Makoto NINOMIYA (JPN) / YANG Zhaoxuan (CHN)