U.S. Open champion Naomi Osaka fought back tears and rallied from a set down to outlast Zhang Shuai 3-6 6-4 7-5 in the China Open quarter-finals on Friday.
Wozniacki claimed her first China Open title in 2010 when she jumped to top the WTA rankings for the first time.
The Australian Open champion got a quick break at the start of the second set too but to her credit Wang battled back to get the score to 3-3.
"As a little kid I had a dream of becoming a professional tennis player, becoming number one in the world".
Argentine top seed Del Potro was far from his best and has been fighting flu or a cold for several days in the Chinese capital.
"I feel like we both have really good serves", she added.
"Then if you win one Grand Slam, they're like, 'Oh, she only won one Grand Slam.' I know it's bad, but I sort of read the comments. I needed to really work it, to work hard, win the points".
The Latvian, who retired from the sport in 2013 citing illness and injury, is seeking a second title of the year after her success at the Bucharest Open in July.
Sevastova has never won against Wozniacki in four career meetings and the Dane has only ever conceded one set to the 28-year-old.
"Unfortunately, I have been playing through pain in my back this whole week", the world number six said in a subsequent statement released by organisers.