Having never faced a compatriot on the WTA Tour before last month, No.9 seed and defending champion Aryna Sabalenka has now clashed with a fellow Belarusian in two of her last three opening rounds. Sabalenka overcame Victoria Azarenka 3-6, 6-3, 6-4 at the US Open and now faces Fed Cup teammate Aliaksandra Sasnovich for the first time.
Two former Top 10 players will bid to turn their form around as Daria Kasatkina takes on Caroline Garcia. Kasatkina is just 9-18 in WTA main draws this season and has slipped from World No.10 at the start of the season to her current World No.40, while Garcia has won just three of her past 12 matches since the Mallorca quarterfinals and has fallen from a career high of World No.4 this time last year to World No.30.
Danielle Collins and wildcard Venus Williams have faced each other once before, with Collins victorious 6-2, 6-3 in last year's Miami quarterfinals.
No.10 seed Sloane Stephens and Zhang Shuai are all square at 2-2 against each other. Stephens, who has won just three of her past 11 matches stretching back to Roland Garros, took the pair's first two meetings, 6-4, 6-2 in the first round of San Diego 2011 and 6-4, 6-0 in the second round of Brussels 2013. However, Zhang has pulled level with a 6-3, 6-1 win in the 2014 Birmingham quarterfinals and a 2-6, 7-6(2), 6-2 comeback in the first round of the 2018 Australian Open.
Dayana Yastremska will take on Ajla Tomljanovic in a rematch of February's Hua Hin final, in which the Ukrainian teenager overturned a 2-5 final set deficit to win her second title 6-2, 2-6, 7-6(3). It was the second win in as many meetings against Tomljanovic for Yastremska, who also won 6-2, 3-6, 6-2 in Beijing qualifying last year.
Wildcard Wang Xiyu will bid for her fifth Top 100 and first Top 50 win over Barbora Strycova. The 18-year-old's best showing against a Top 50 player so far was in stretching Daria Kasatkina to a third set and holding four match points in the third round here last year before falling 6-1, 3-6, 7-6(8). Strycova has yet to win a main draw match since reaching the Wimbledon semifinals.
Qualifier Zhu Lin won her only previous encounter with wildcard and Nanchang finalist Elena Rybakina 6-2, 6-4 in Australian Open qualifying this year.
ORDER OF PLAY
CENTER COURT (starts 12 noon)
[WC] Venus WILLIAMS (USA) vs Danielle COLLINS (USA)
 Aryna SABALENKA (BLR) vs Aliaksandra SASNOVICH (BLR)
Opening Ceremony and Li Na Tennis Hall of Fame Tribute
Not before 7.30pm
ZHANG Shuai (CHN) vs  Sloane STEPHENS (USA)
Barbora STRYCOVA (CZE) vs [WC] WANG Xiyu (CHN)
COURT 1 (starts 11am)
Jessica PEGULA (USA) vs Polona HERCOG (SLO)
Ajla TOMLJANOVIC (CRO) vs Dayana YASTREMSKA (UKR)
[Q] Jennifer BRADY (USA) vs [Q] Bernarda PERA (USA)
Not before 4pm
Daria KASATKINA (RUS) vs Caroline GARCIA (FRA)
[WC] Elena RYBAKINA (KAZ) vs [Q] ZHU Lin (CHN)
[WC] TANG Qianhui (CHN) / WANG Xinyu (CHN) vs Simona HALEP (ROU) / Raluca OLARU (ROU)