No.1 seed and last year's runner-up Simona Halep will seek to snap a three-match losing streak against qualifier Ons Jabeur in a battle of former Roland Garros junior champions. Halep has not lost four consecutive Tour matches since the start of 2016, when she fell to Svetlana Kuznetsova in the Sydney semifinals and followed that with opening-round defeats at the Australian Open to Zhang Shuai, in Dubai to Ana Ivanovic and in Doha to Elena Vesnina. That run was punctuated by a victory in Fed Cup play, though; the last time the Romanian lost four straight matches overall was in 2012, when she followed defeat in the Brussels final at the hands of Agnieszka Radwanska with first-round stumbles at Roland Garros to Petra Cetkovska, both 's-Hertogenbosch and Wimbledon to Anabel Medina Garrigues and the London Olympic Games to Yaroslava Shvedova.
No.12 seed Kiki Bertens is yet to defeat Sorana Cirstea in four attempts. The Cincinnati and Seoul champion comes into Beijing having won 21 of her past 25 matches, but has lost to Cirstea on clay (Roland Garros 2013), outdoor hard courts (Washington 2014), indoor hard courts (Linz 2016) and grass (Wimbledon 2017).
No.9 seed Sloane Stephens won her only previous encounter with Anastasia Pavlyuchenkova emphatically, 6-1, 6-2 in the 2015 Washington final - a result that netted her maiden title. However, the American enters Beijing on a three-match losing streak - and a seven-match losing streak in Asia, having not won a match on the continent since 2015. Stephens' career-best showing in Beijing was her 2013 run to the third round.
Three home wildcards are in action today: Wang Yafan against Caroline Garcia, Zheng Saisai against Dayana Yastremska and Duan Yingying against Dominika Cibulkova. Since Beijing became a Premier Mandatory event in 2009, the deepest local runs have been Li Na's semifinal showings in 2010 and 2012; the most successful Chinese wildcard was Zhang Shuai, who defeated World No.1 Dinara Safina to reach the third round in 2009.
Defending champion Caroline Garcia was lifted into the Top 10 for the first time after winning the title last year - but the Frenchwoman has never successfully defended a title, and after falling at the first hurdle in Wuhan last week a similar failure to do so in Beijing could see her fall back out of the Top 10.
No.3 seed Angelique Kerber leads her head-to-head against Kristina Mladenovic 3-1, including a 6-7(4), 6-1, 6-4 win in the third round of Wuhan in 2016 - but the Frenchwoman's sole victory was in their last meeting, 6-2, 7-5 in the second round of Stuttgart last year.
Alizé Cornet won her first ever encounter with Anastasija Sevastova in Paris in 2009, but since then has lost three straight matches to the Latvian: twice in Monterrey from a set up, in 2010 and 2011, and in straight sets this year, 7-5, 6-4 in the second round of Miami.
No.17 seed Madison Keys faces compatriot Bernarda Pera for the third time this year. In the Charleston quarterfinals, Keys had to come from a break down in the third set to win 6-2, 6-7(5), 7-5, but eased past more smoothly 6-4, 6-1 in the second round of the US Open.
CoCo Vandeweghe will aim to snap an eight-match losing streak stretching back to 's-Hertogenbosch in June in her first meeting with Polona Hercog. The American has taken five of this string of defeats to a deciding set, but was forced to retire in two of those; she has won just one match in Beijing in five previous visits.
ORDER OF PLAY (all courts start 12.30pm)
NATIONAL TENNIS STADIUM
Angelique KERBER (GER)  vs Kristina MLADENOVIC (FRA)
[WC] WANG Yafan (CHN) vs Caroline GARCIA (FRA) 
Simona HALEP (ROU)  vs [Q] Ons JABEUR (TUN)
Not before 7.30pm
Sloane STEPHENS (USA)  vs Anastasia PAVLYUCHENKOVA (RUS)
(LL) Sorana CIRSTEA (ROU) vs Kiki BERTENS (NED) 
[WC] ZHENG Saisai (CHN) vs [Q] Dayana YASTREMSKA (UKR)
[LL] Bernarda PERA (USA) vs Madison KEYS (USA) 
[WC] DUAN Yingying (CHN) vs Dominika CIBULKOVA (SVK)
Desirae KRAWCZYK (USA) / Sabrina SANTAMARIA (USA) vs [WC] JIANG Xinyu (CHN) / WANG Qiang (CHN)
Daria KASATKINA (RUS)  vs Laura SIEGEMUND (GER)
[WC] Johanna KONTA (GBR) / ZHANG Shuai (CHN) vs Aleksandra KRUNIC (SRB) / Katerina SINIAKOVA (CZE)
Anastasija SEVASTOVA (LAT) vs Alizé CORNET (FRA)
Kirsten FLIPKENS (BEL) vs [Q] Katie BOULTER (GBR)
After 2 ATP matches
Mihaela BUZARNESCU (ROU) / Monica NICULESCU (ROU) vs CHAN Hao-Ching (TPE) / YANG Zhaoxuan (CHN) 
Timea BABOS (HUN) vs HSIEH Su-Wei (TPE)
[Q] Andrea PETKOVIC (GER) vs Lesia TSURENKO (UKR)
CoCo VANDEWEGHE (USA) vs [Q] Polona HERCOG (SLO)
After 2 ATP matches
Daria GAVRILOVA (AUS) / Laura SIEGEMUND (GER) vs Nadiia KICHENOK (UKR) / Anastasia RODIONOVA (AUS)
Alicja ROSOLSKA (POL) / Abigail SPEARS (USA) vs Monique ADAMCZAK (AUS) / Heather WATSON (GBR)
After 1 ATP match
Andreja KLEPAC (SLO) / María José MARTÍNEZ SÁNCHEZ (ESP)  vs Timea BACSINSZKY (SUI) / Ajla TOMLJANOVIC (AUS)