Hometown hero Naomi Osaka recovered from a sluggish start to beat Bulgarian qualifier Viktoriya Tomova 7-5 6-3 and reach the quarter-finals at the Pan Pacific Open in Japan on Wednesday.
Making her first appearance at the tournament after a first-round bye, Osaka's serve looked shaky in the early stages and she soon found herself down a double-break to Tomova at 3-0.
The top seed pulled herself back into the contest with her trademark powerful forehands and crisp volleys before Tomova double faulted in the 12th game to concede the opening set.
Osaka switched gears in the second set to finish the match with 40 winners, including 13 blistering aces, and pass an awkward opening test she received from world number 181 Tomova.
Last week, Osaka stunned the tennis world by sacking her second coach in seven months, parting ways with Jermaine Jenkins after a disappointing U.S. Open title defence.