Svitolina booked her place in Sunday's championship match when her Swiss opponent was forced to retire due to a leg cramp at the one hour, 56-minute mark.
Bencic took an early lead in the first set on Saturday and wrapped up the opener by breaking serve for the second time in an intense 12th game, reports Efe news.
But her physical problems were already apparent and they forced her to take a medical timeout after the 11th game for treatment on her right hamstring. Those visits from the trainer then continued over the remainder of the match.
Later, the 22-year-old Swiss said she was disappointed that her body let her down after a long, successful season in which was able to avoid the injuries that have plagued her career and made her way back into the top 10 for the first time since 2016.
The 25-year-old Svitolina, whose biggest title of her career came at last year's WTA Finals in Singapore, will be seeking her first title of 2019 late on Sunday.
Her opponent will be 23-year-old Australian world No. 1 Ashleigh Barty, who continued her meteoric rise this season by capturing her maiden Grand Slam title (at the French Open), taking over the No. 1 spot in the rankings for the first time in her career in June and booking a berth in the WTA Finals' singles competition for the first time here in Shenzhen.
The WTA Finals is the most prestigious event on the women's tennis calendar after the four Grand Slam tournaments.
( With inputs from IANS )