Top seed Karolina Pliskova cannot qualify for the WTA Finals this week, but is on course to feature in Singapore.
Croatian Donna Vekic tumbled out of the Linz Open on Tuesday, the eighth seed winning just two games.
Seeds Elina Svitolina and Garbine Muguruza recorded straightforward victories on Tuesday to reach the last 16 in Hong Kong.
Seeds Dominic Thiem and Marin Cilic were surprise casualties at the Shanghai Masters as they crashed out at the round-of-32 stage.
Jeremy Chardy remains without a win against a top-three opponent and Novak Djokovic after the Serbian won their Shanghai Masters clash.
Timea Bacsinszky was victorious on the WTA Tour for the first time since last year's Wimbledon at the Tianjin Open.
There were contrasting fortunes for seeds Magdalena Rybarikova and Anastasia Pavlyuchenkova at the Linz Open on Monday.
Having reached the semi-finals of the China Open, Naomi Osaka has risen to fourth in the WTA rankings.
Kristina Kucova had not won a WTA main draw match in over a year but she came from a set down to beat Jelena Ostapenko.
Despite losing the first set to Stan Wawrinka, Borna Coric took the next two to advance to the last 32 at the Shanghai Masters.