World number one Simona Halep was forced to retire from the China Open in the first round due to injury.
The Romanian lost the first set 6-1 to Tunisia's Ons Jabeur in Beijing before succumbing to the back injury after 31 minutes.
Halep, 27, suffered the injury a week ago in Wuhan.
Defending champion Caroline Garcia from France beat China's Wang Yafan 7-6 (12-10) 6-7 (4-7) 6-3 to reach the second round.
Third seed Angelique Kerber from Germany also progressed with a 6-2 6-2 win over France's Kristina Mladenovic.
British number one Johanna Konta suffered a first-round defeat by German 10th seed Julia Gorges on Saturday.