Following an opening-round win over Germany’s Tamara Korpatsch on Monday, Osaka looked to keep her momentum going against the Czech world number 39 but was ultimately outlasted 3-6 7-6 (4) 6-4.
In a battle of two former world number ones, Osaka exploded out of the gates to claim the first set before Pliskova began to find her footing in the second.
After surviving an early break point, Pliskova capitalised on her serve to take control of the match, going on to win 92 percent of her first service points in the set.
Osaka continued to threaten throughout the final set, but was unable to make the most of her remaining opportunities in the narrow loss.
Osaka returned to the court on Monday for the first time since withdrawing from the Pan Pacific Trophy with a knee injury in September 2021. She became a mother for the first time in July.
Elsewhere, Australia’s Daria Saville came agonisingly close to upsetting 11th seed Anastasia Potapova in a 6-4 3-6 6-4 defeat.
The world number 176 dropped the first set but battled back to convincingly claim the second in front of a raucous home crowd.
However Potapova showed plenty of her own fight in the decider, eventually wrapping up the result in two hours and 52 minutes.
Meanwhile, top seed Aryna Sabalenka swept past Italy’s Lucia Bronzetti 6-3 6-0 and sixth seed Veronika Kudermetova cruised to a 6-2 6-3 win over world number 73 Anna Karolina Schmiedlova.
