Garbine Muguruza put on an exhibition in the second set after being tested in the first by Monica Puig in Tokyo.
Denis Istomin produced an early shock at the Moselle Open as he dumped out sixth seed Richard Gasquet in the first round.
Top seed Peng Shuai saved 10 break points in the deciding set against Ons Jabeur to progress at the Guangzhou Open.
Former champion Mikhail Youzhny made a winning start to his latest quest for a second St. Petersburg Open crown.
Having lost in the Connecticut Open final last month, Dominika Cibulkova began her Pan Pacific Open campaign with a straight-sets win.
While Jelena Ostapenko made serene progress in Seoul, fellow top-three seeds Kiki Bertens and Kristyna Pliskova suffered defeats.