Zheng Saisai pulled off an upset on day one of the WTA Elite Trophy by stunning Madison Keys.
The Chinese secured her third top-20 win of the year as the wildcard claimed a routine straight-sets win over the number three seed in Zhuhai.
Keys won the only previous clash between the two, which took place in Zhuhai four years ago, but the world number 37 needed only 91 minutes to prevail 6-4 6-2 and claim a key win in the Orchid Group.
While Keys floundered, Kiki Bertens made a winning start to her campaign by wearing down Donna Vekic in a tough opening encounter.
Bertens is the top-ranked player at the event, but the world number 10 did not have it easy in her fourth meeting of the year with Vekic.
The Dutchwoman squandered two match points in losing to Vekic in Brisbane but has now beaten the Croatian in three successive matches after a 7-6 (7-5) 6-2 win in southern China.
Bertens needed an hour and 20 minutes to claim the first set in a tie-break, but raced to a 5-0 lead in the second to kick off the Azalea Group with a straight-sets success.
Explaining how she has maintained her drive after missing out on a WTA Finals berth, Bertens said: "I really had that goal in mind and now it was a little bit gone.
"But still, once I'm on court I want to win - and this tournament. I still want to win. [It's] really in me that I always want to win, so I think that's my drive."
The Rose Group started with a comfortable win for Aryna Sabalenka, who saw off Maria Sakkari 6-3 6-4.