Taiwan's Hsieh Su-Wei overpowered American qualifier Amanda Anisimova 6-2, 6-2 on Sunday to win the Japan Women's Open.
Second-seeded Hsieh converted five of six break points against the 17-year-old Anisimova, who was playing in her first WTA final.
Anisimova, who turned 17 just two weeks ago, was the youngest player to reach a final since 16-year-old Donna Vekic at Tashkent in 2012 and Birmingham in 2013.
She lacked the poise that allowed her to reach Sunday's final, double faulting five times and making 23 unforced errors.
Hsieh never faltered and finished with 14 winners to just six unforced errors to claim her third career title.