No.3 seed Elina Svitolina has split two previous meetings with last year's runner-up Anastasija Sevastova. Svitolina was victorious in their first clash 6-3, 7-6(7) in the first round of the 2013 Cali 125K, where she would go on to reach the semifinals before falling to Catalina Casta?o, but Sevastova would gain revenge in the fourth round of last year's US Open, winning 6-3, 1-6, 6-0 en route to her maiden Grand Slam semifinal.
No.10 seed Angelique Kerber faces a rematch of last year's third round tie here against Zhang Shuai, which Zhang won 6-1, 2-6, 6-0 en route to her second Beijing quarterfinal. Kerber - whose own best Beijing runs have been a triptych of quarterfinals in 2012, 2013 and 2015 - won their only other previous meeting 6-3, 6-4 in the first round of Roland Garros 2012.
Former World No.1 Venus Williams has never lost to Wimbledon semifinalist Barbora Strycova in four previous meetings, including two on hard courts. The American conceded only three games in their first and most recent encounters, in the 2009 Acapulco semifinals and the second round of Montréal 2016, but in between came out on top of two three-set battles, 6-3, 0-6, 7-5 in the first round of Charleston 2014 and 7-5, 3-6, 7-6(5) in the third round of Doha 2015.
No.6 seed and 2017 runner-up Simona Halep has faced qualifier Rebecca Peterson once before, winning 6-4, 6-0 in the first round of Bastad 2013 - the second WTA main draw match of a 17-year-old Peterson's career. Nanchang champion Peterson is bidding for her second Top 10 win of the season after her first-round upset of Sloane Stephens in Washington.
Dayana Yastremska and 2017 champion Caroline Garcia face off in a rematch of this year's epic Strasbourg title match - the longest final of the year to date at two hours and 58 minutes, won by Yastremska 6-4, 5-7, 7-6(3) after saving one match point.
2006 and 2009 champion Svetlana Kuznetsova has split four previous meetings against qualifier Christina McHale, having lost their first two encounters in 2011 in the first rounds of Indian Wells and New Haven, but levelled the head-to-head with wins in the second round of Auckland 2012 and the first round of Roland Garros 2017.
No.13 seed Sloane Stephens defeated qualifier Magda Linette 6-2, 6-1 in their only previous meeting, in the first round of Washington 2015 - going on to claim her maiden WTA title. Bronx champion and Seoul finalist Linette is bidding for her second career Top 20 win following her defeat of Naomi Osaka at Washington 2018.
No.4 seed and 2018 semifinalist Naomi Osaka faces Washington champion Jessica Pegula for the first time. Pegula is bidding for her third career Top 20, and first Top 10, win.
An all-Chinese derby finds Acapulco champion Wang Yafan taking on 18-year-old wildcard Wang Xinyu, who has compiled a 28-6 win-loss record including three ITF titles over the past four months. Yafan was the victor in their only prior clash, 6-4, 6-4 in the first round of last year's Jinan ITF 60K event.
ORDER OF PLAY (all courts start 12.30pm)
Jessica PEGULA (USA) vs  Naomi OSAKA (JPN)
Barbora STRYCOVA (CZE) vs Venus WILLIAMS (USA)
 Elina SVITOLINA (UKR) vs Anastasija SEVASTOVA (LAT)
Not before 7.30pm
 Angelique KERBER (GER) vs ZHANG Shuai (CHN)
 WANG Qiang (CHN) vs Ajla TOMLJANOVIC (AUS)
[WC] WANG Xinyu (CHN) vs WANG Yafan (CHN)
 Simona HALEP (ROU) vs [Q] Rebecca PETERSON (SWE)
Caroline GARCIA (FRA) vs Dayana YASTREMSKA (UKR)
Not before 5.30pm
[Q] Magda LINETTE (POL) vs  Sloane STEPHENS (USA)
Danielle COLLINS (USA) vs Kristina MLADENOVIC (FRA)
[Q] Christina MCHALE (USA) vs [WC] Svetlana KUZNETSOVA (RUS)
Karolina PLISKOVA (CZE) / Kristyna PLISKOVA (CZE) vs Lyudmyla KICHENOK (UKR) / Desirae KRAWCZYK (USA)
Ekaterina ALEXANDROVA (RUS) vs [Q] Bernarda PERA (USA)
After 2 ATP matches
Jil TEICHMANN (SUI) vs [Q] Andrea PETKOVIC (GR)
Shuko AOYAMA (JPN) / Ena SHIBAHARA (JPN) vs Anna BLINKOVA (RUS) / Renata VORACOVA (CZE)
Kateryna BONDARENKO (UKR) / Aleksandra KRUNIC (SRB) vs Darija JURAK (CRO) / María José?MARTíNEZ SáNCHEZ (ESP)
Yulia PUTINTSEVA (KAZ) vs [Q] Anna BLINKOVA (RUS)
Jennifer BRADY (USA) / Katarina SREBOTNIK (SLO) vs  Nicole MELICHAR (USA) / Kveta PESCHKE (CZE)