Fifth seed Dominika Cibulkova got her Toray Pan Pacific Open campaign under way with a first-round win over Carla Suarez Navarro.
The Slovak, who is yet to win a title this season, edged out the Spaniard 6-3 6-3.
Ninth seed Caroline Garcia also prevailed in comfortable style, seeing off Aliaksandra Sasnovich 6-4 6-3 while Monica Puig prevailed against Hsieh Su-wei and Anastasia Pavlyuchenkova had too much for Cici Bellis.
Shelby Rogers, Daria Kasatkina, Magda Linette and Katerina Siniakova also made it through.
French Open champion Jelena Ostapenko booked her place in the next round of the Korea Open by downing Sweden's Johanna Larsson.
Ostapenko edged a tight first set before stretching her legs in the second to seal a 7-6 (7/6) 6-1 victory.
There were also wins for Richel Hogenkamp, Denisa Allertova, Arantxa Rus, Na-Law Han, Naomi Gibbs and Kai-Chen Chang.
At the Guangzhou Open in China, former US Open champion Sam Stosur was beaten by home player Xinyun Han, who won the last five games of the match to take a 6-7 (6/8) 6-3 7-5 win while Alize Cornet beat Bernarda Pera 4-6 6-2 6-2.
Evgeniya Rodina, Zhang Kailin, Wang Yafan, Lizette Cabrera, Zhang Shuai and Peng Shuai also progressed.
Source: PA
