US Open champion Naomi Osaka has pulled out of this week's Hong Kong Open to prevent aggravating a slight back injury, organizers said on Sunday.
Sevastova is set to play the final against the victor of the match between Caroline Wozniacki of Denmark, the second seed and victor of the Australian Open this year, and wildcard Wang Qiang of China.
In the other semi-final, Sevastova defeated Japan's world number eight Osaka, 6-4, 6-4 for her fourth top 10 win of the season.
Anastasija Sevastova beat U.S. Open champion Naomi Osaka 6-4, 6-4 Saturday to reach the China Open final. "I was basically apologising because I feel like today I was more emotional than what I normally am trying to be like", said the world number six.
The 28-year-old, who won her first Grand Slam at the Australian Open at the start of this year, was imperious against the unseeded Sevastova.
Osaka had been close to tears during the second set and threw her racquet, before recovering her poise.
"I think I played really well, probably the best match for me in the tournament". Last week, she got to the Pan Pacific Open final in Tokyo.
The time off allowed her body to mend and she returned to the sport in January 2015.
The Latvian, seeking what would have been the biggest title of her career, was ultimately her own worst enemy though, committing 35 unforced errors, 21 of them in the second set.
The Argentine top seed Del Potro will face either Britain's fifth seed Kyle Edmund or unseeded Nikoloz Basilashvili of Georgia.