Ashleigh Barty is the only seed in the quarter-finals of the Wuhan Open after Caroline Wozniacki and Garbine Muguruza crashed out in the night session.
Barty beat Angelique Kerber 7-5 6-1 on Wednesday before two-time champion Petra Kvitova fell to Anastasia Pavlyuchenkova, a day after world number one Simona Halep was bundled out by Dominika Cibulkova.
The upsets continued to come thick and fast on day four, with Monica Puig claiming the scalp of second seed Wozniacki, winning 7-6 (12-10) 7-5.
Qualifier Katerina Siniakova came back from 5-1 down in the first set to see off Muguruza 7-6 (7-3) 7-6 (7-1) in the early hours of Thursday morning, leaving Barty as the solitary seed in the last eight.
Cibulkova earlier ousted Daria Kasatkina, the 13th seed, in a tournament that is wide open, with Wang Qiang advancing in her homeland along with Aryna Sabalenka and Anett Kontaveit.
MORE MISERY FOR WOZNIACKI
Wozniacki has won just twice since taking her second title of the year at Eastbourne in June and Puig capitalised on the world number two's loss of form.
Puig beat the Dane at the Miami Masters in March and it was the same story in China, the Olympic champion winning a seventh match point to set up an encounter with Wang.
Wozniacki won the first three games of the match but failed to build on that strong start, losing the first set after seeing three set points come in go in a long tie-break.
Puig also came from behind in the second set, rallying from 3-1 down to get the job done in two hours and 24 minutes.
FEARLESS SINIAKOVA GOES FROM STRENGTH TO STRENGTH
Siniakova beat defending champion Caroline Garcia on Tuesday after saving a match point and the Czech battled back again to account for a furious Muguruza.
Two-time grand slam champion Muguruza appeared to be coasting in the first set, but Siniakova won four games in a row to level at 5-5 and sealed the breaker with an aggressive approach.
Muguruza paid the price for 46 unforced errors as she squandered a 4-2 lead in the second to bow out.
Kontaveit will be Siniakova's opponent at the quarter-final stage after the Estonian defeated Zhang Shuai 6-4 4-6 6-1.
BARTY ON COURSE TO GO ONE BETTER
Barty was beaten by Garcia in the Wuhan final last year and the Australian stayed in contention to go one better.
The 16th seed accounted for Wimbledon champion Kerber in straight sets for a first win over a top 10 player in a year.
"She's always very difficult to play against. She's one of the best players in the world, and you have to come out here, enjoy and have fun, and try and play as well as you can," said Barty, who will now take on Pavlyuchenkova.