Reigning US Open Champion Naomi Osaka overcame some emotions to scrape past Zhang Shuai and reach the Semi Finals of the China Open.
Wozniacki claimed her first China Open title in 2010 when she jumped to top the WTA rankings for the first time.
Wozniacki is also the reigning WTA Finals and Australian Open champion and the highest ranked player left in the tournament following world number one Simona Halep's first round retirement.
"Unfortunately, I have been playing through pain in my back this whole week and the doctors have advised me that I need to rest to ensure the injury is not further aggravated and become more serious", she added.
In the men's final, Juan Martin del Potro faced Nikoloz Basilashvili of Georgia.More news: Drew Brees breaks National Football League career pass yards record
More news: Hamilton cruises to win at Japanese GP, closes in on title
More news: Cristiano Ronaldo in contention for third successive Ballon d'Or
World No. 8 Naomi Osaka of Japan breezed into the quarterfinals of the China Open here on Thursday with a domineering straight-set victory over Germany's Julia Goerges 6-1, 6-2.
Sevastova has never won against Wozniacki in four career meetings and the Dane has only ever conceded one set to the 28-year-old.
"Then after number one in the world, I wanted to win a Slam, then I wanted to lift trophies".
Wang's quarter-final win over Aryna Sabalenka was her 16th from her last 18 matches in her homeland, but she found herself under early pressure here and was broken in her opening service game when she netted a backhand.
"I think I had a dream of that, but I don't know how realistic I really believed that was going to be".