After a close beginning, Osaka won five games in a row, stretching into the second set. Bouzkova would go up a break, but the defending champion won the final four games to seal a second round meeting with Saisai Zheng.
Osaka finishes strong in both sets to advance
Both players settled into the match with love holds to begin, but it was the 59th-ranked Bouzkova who earned the first break point of the match, but Osaka was up to the task with a fine backhand that eventually led to a hold and a 2-1 lead.
The world number three then sharpened her game and her focus to soon find herself up 0-40, but some superb play from the Czech saw her save all three and eventually a fourth, but when a fifth arose, Osaka pounced and took a 3-2 lead.
The Czech was playing some nice tennis, but crucial mistakes at the worst times put her in this deficit and she double-faulted to bring up double break point and handed the defending champion a second break with an easy backhand miss. Osaka was taken to 30-30, but closed out the set two points later.
Bouzkova pulled out a scrappy hold before getting to 15-40 on Osaka's serve, but the Japanese star saved herself with some clutch serving, an ace punctuating the game. The Czech was facing a break point in the third game only to watch Osaka gift her that and the next game with a series of errors for a 3-2 edge.
The world number 59 showed why she reached the semifinals in Canada last summer and some stupendous returning baited Osaka into more errors and the Czech broke for a 4-2 lead. A slice of fortune turned the set around as the third seed's mishit return landed in the corner and on break point, Bouzkova double-faulted to put the set back on serve.
Osaka's ground game was starting to round into form and as she saw 0-30 turn into 30-30, pinpoint returning got her the break and a 5-4 advantage. Serving for the match, she held to 15, a final Bouzkova backhand skittering wide and the title holder was safely through.