Four-time Grand Slam title winner Osaka, who is rebuilding her career after maternity leave, went down 7-6 (8/6), 7-6 (7/5) after saving three match points
Osaka won the first set but Pliskova fired 16 aces and hit 50 winners, saving 10 of the 12 breakpoints she faced and making amends for her 11 double-faults