Simona Halep's was unceremoniously dumped out of the Wuhan Open by Daria Kasatkina and Caroline Wozniacki also made an early exit, but Garbine Muguruza reached the third round on Tuesday.
Halep had not played since losing to Maria Sharapova in the first round of the US Open and looked rusty in a crushing 6-2 6-1 loss to unseeded Russian Kasatkina, which put paid to her hopes of replacing Muguruza at the top of the rankings.
Kasatkina knocked French Open champion Jelena Ostapenko out at Flushing Meadows and has also beaten Angelique Kerber this year.
The 20-year-old world number 31 made light work of claiming the scalp of second seed Halep, breaking the disgruntled French Open runner-up four times in the first set and twice in the second to ease through.
Wozniacki thrashed Muguruza at the semi-final stage en route to retaining her Tokyo Open title last week, but the fourth seed suffered a shock 7-5 6-3 loss to qualifier Maria Sakkari.
Muguruza required treatment in the first set, but saw off Lesia Tsurenko 6-4 6-4 after having her tape applied to her left thigh.
Sixth seed Svetlana Kuznetsova went down 6-3 6-3 to Alize Cornet a day after Sloane Stephens and defending champion Petra Kvitova were among the seeded casualties.
Karolina Pliskova, Dominika Cibulkova, new Korea Open champion Ostapenko, Agnieszka Radwanska and Elena Vesnina had no such trouble as they advanced to the last 16.
'NO DRAMA' BUT BEATEN HALEP VOWS TO LEARN FROM DEFEAT
Halep opted to take a break after falling at the first hurdle to Sharapova in New York and plans to hold an inquest after her latest setback.
The Romanian said: "I didn't play for, like, a month. It's tough to come back and to play matches. The rhythm of the match, the rhythm of the big points. It's tough to get that rhythm quickly, in a few games. Maybe it was a mistake that I didn't play, but I needed rest after the US season.
"I think she played really well today, and everything went in the right way for her. But also it wasn't my best day. It's tough. I take it like it is. No drama. But for sure I will talk about this match and I will learn more things about it."
SAKKARI BRINGS WOZNIACKI BACK DOWN TO EARTH
Wozniacki claimed her first title of what has been an impressive year by defeating Anastasia Pavlyuchenkova in Toyko on Sunday, but was stunned by Sakkari two days later.
The Dane's exploits in Japan appeared to have caught up with her and the Greek world number 80 took advantage, securing the biggest win of her career.
Wozniacki has won more singles matches than any other players on the WTA tour this year, but the Wuhan debutant ensured the former world number one failed to add to her tally.
Sakkari unleashed a barrage of winners and reaped the rewards of an aggressive approach, Wozniacki racking up 37 unforced errors in a bad day at the office in which she was broken on five occasions.
HALEP AMONG QUARTET TO SEAL SINGAPORE SPOTS
There was some good news for Halep when it was confirmed that she is among another four players to have qualified for the season-ending WTA Finals in Singapore.
Pliskova, Elina Svitolina and Venus Williams have also joined Muguruza in sealing their spots in the lucrative tournament.
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