Beijing - World number one Simona Halep is out of the China Open at the first hurdle, retiring with back trouble after losing the first set 6-1 to Ons Jabeur on Sunday.
The Romanian's tournament lasted just 31 miserable minutes in Beijing and she never looked comfortable against the Tunisian qualifier.
Halep, 27, suffered the back injury a week ago in Wuhan.
The top-ranked Halep's early departure is another blow to organisers in the Chinese capital, with Serena Williams missing from the women's draw and several big names also absent from the men's event.
Holder Caroline Garcia is at least in action, but she survived a major scare before defeating wildcard Wang Yafan 7-6 (12/10), 6-7 (4/7), 6-3 to open the defence of her crown.
The 24-year-old from France defied a rattling roof and a surprisingly stiff challenge from the home player to labour into round two on Beijing's hard courts after more than three hours of nervy action.
Garcia took the first set on a tie-break after 77 minutes during which the retractable roof - which was closed - banged noisily on occasion in the wind.
The fourth-ranked French player and Wang, 78th in the world, went to battle again in the second set and Garcia came back to force another tie-break.
Garcia, who won back-to-back titles last year in China in a breakthrough 2017, rescued one set point in the tie-break but Wang made the second count to force a deciding set.
Garcia was more ruthless this time, racing into a 3-0 lead as the 24-year-old Wang's fighting spirit was finally nullified.
Results from the WTA/ATP China Open on Sunday in Beijing (x denotes seed):
Ons Jabeur (TUN) bt Simona Halep (ROU x1) 6-1, retired
Anastasija Sevastova (LAT) bt Alize Cornet (FRA) 6-4, 6-2
Madison Keys (USA x17) bt Bernarda Pera (USA) 6-3, 6-4
Zheng Saisai (CHN) bt Dayana Yastremska (UKR) 6-4, 6-3
Dominika Cibulkova (SVK) bt Duan Yingying Duan (CHN) 6-3, 6-2
Angelique Kerber (GER x3) bt Kristina Mladenovic (FRA) 6-2, 6-2
Timea Babos (HUN) bt Hsieh Su-Wei (TPE) 6-2, 6-2
Lesya Tsurenko (UKR) bt Andrea Petkovic (GER) 6-2, 7-6 (7/2)
Polona Hercog (SLO) bt Coco Vandeweghe (USA) 6-2, 6-1
Caroline Garcia (FRA x4) bt Wang Yafan (CHN) 7-6 (12/10), 6-7 (4/7), 6-3
Laura Siegemund (GER) bt Darya Kasatkina (RUS x13) 6-3, 4-2 retired