Naomi Osaka advanced to the quarterfinals of the Porsche Tennis Grand Prix with a straight-sets win over Taiwan's Hsieh Su-wei on Thursday.
The world No. 1 avenged her upset loss to Hsieh at the Miami Open last month with a 6-4, 6-3 victory at Stuttgart's Porsche-Arena.
The 20-year-old Japanese served seven aces and did not concede a break point as she overpowered her unseeded opponent in 1 hour, 24 minutes.
Osaka, who won her second Grand Slam at this year's Australian Open, hit 22 winners to just 16 unforced errors while converting three of her six break points against world No. 24 Hsieh.
The No. 1 seed started the indoor clay court tournament in the round of 16 following an opening-round bye.
Her quarterfinal opponent will be Croatian Donna Vekic, who advanced with a 6-1, 7-5 victory over Daria Kasatkina of Russia.