But Wang hit back with two breaks of her own to reduce the deficit to 4-3, only to give her serve away in a lengthy eighth game.
In this match Muguruza defeated Sevastova and reached the semifinals of the tournament in Zhuhai.
And after a slow start on Saturday night (AEDT) the popular world No.19 made the most of her good fortune with a 4-6 6-3 6-2 victory over Goerges.
Wang was a late replacement for original group-stage victor Madison Keys after the American withdrew from the semifinal with a left knee injury.
The Spaniard, a two-time Grand Slam champion, also saved eight of 12 break points against her second-seeded opponent.
And with it comes a projected rise to No.15 in the world when the WTA rankings are released on Monday, positioning her well for an all-important top-16 seeding at January's Australian Open. This time, she surrendered to Barty in straight sets before beating Sabalenka for the first time in her career. Barty consolidated her level in tennis and broke into the top 20 in the world.
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While Barty flourished, Wang sprayed the ball wide and long all too often and, although she got back into the set, nothing was going to stop her opponent moving ahead. "I'm very excited that it's finished now, time for some vacation and "relax" time before we gear up for the Australian summer".
"I didn't think about what to improve", she said.
The ninth seed grew into the semi-final match against Germany's Goerges, seeded fifth, and dominated the third set to book her place in Sunday's showdown in Zhuhai.
Barty served out a thrilling first set in 37 minutes with an overhead smash and the second set proved to be a battle of patience for both players.
It is her third WTA singles title, adding to her breakthrough 2017 trophy at the Malaysian Open and this year's grasscourt win in Nottingham.