Iga Swiatek, seeded first, defeated Elise Mertens 6-3, 6-4 to move forward to the quarterfinals of the Porsche Grand Prix on Thursday.
Next up for Swiatek is Emma Raducanu, who secured her spot after beating Linda Noskova 6-0, 7-5.
In another match, fourth-seeded Elena Rybakina had a tough journey into the quarterfinals with a 7-6 (3), 1-6, 6-4 victory over Veronika Kudermetova.
Rybakina faced challenges during the game but managed to hold off-break points in the first set and win the tiebreaker. However, Kudermetova dominated the second set as Rybakina made more mistakes.
In the final set, Rybakina took control again, leading 4-1 before allowing Kudermetova to level. Despite the setback, Rybakina rallied and secured a tight service hold to win the match.
She will face Jasmine Paolini in the next round after Paolini upset seventh-seeded Ons Jabeur 7-6 (8), 6-4.
Markéta Vondroušová, seeded sixth, also advanced to the quarterfinals after defeating Anastasia Potapova 7-6 (5), 6-1. Vondroušová will play against second-seeded Aryna Sabalenka in the next match.
The tournament features eight of the top 10 ranked women and is the main event in the first week of clay tournaments on the WTA Tour.