Jelena Ostapenko was a surprise first-round casualty at the Hong Kong Open.
The Latvian third seed, a former French Open champion, was beaten 5-7 6-3 6-2 by world number 317 Kristina Kucova of Slovakia.
Eighth seed Alize Cornet had no such trouble, running out a comfortable 6-1 6-2 winner against Julia Glushko.
There were also first-round wins for Thailand's Luksika Kumkhum, Ukrainian Dayana Yastremska and Viktoriya Tomova of Bulgaria.
Tomova, who survived a final set tie-break against Dalila Jakupovic, will face Kucova in round two.
At the Tianjin Open in China, top seed Karolina Pliskova needed three sets to overcome America's Varvara Lepchenko and reach the second round.
Pliskova, from the Czech Republic, dropped the second set on a tie-break but battled through 6-2 6-7 (3) 6-3.
Fifth seed Hsieh Su-wei of Taiwan beat Australia's Ajla Tomljanovic 7-6 (4) 7-5 and Petra Martic of Croatia, seeded sixth, required a third-set tie-break to edge past home hope Ying-Ying Duan 3-6 6-3 7-6 (3).
At the Linz Open in Austria, Russian sixth seed Anastasia Pavlyuchenkova, the 2015 champion, advanced into the second round with a 7-5 7-5 victory over Viktoria Kuzmova.
Kuzmova's fellow Slovakian Magdalena Rybarikova, the seventh seed who was the beaten finalist last year, was defeated 6-3 6-4 by Alison Van Uytvanck of Belgium.
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