World No. 1 Iga Swiatek of Poland opened her title defense at the Porsche Tennis Grand Prix with a 6-1, 6-4 win over Qinwen Zheng of China in second-round action Thursday in Stuttgart, Germany.

Swiatek broke Zheng’s serve four times in eight opportunities and won 27 of 32 first-service points (84.4 percent).

She will draw former world No. 1 Karolina Pliskova of the Czech Republic in the quarterfinals after Pliskova pushed past Croatia’s Donna Vekic 6-2, 6-7 (5), 7-6 (5) in two hours and 20 minutes.

Fourth-seeded Frenchwoman Caroline Garcia defeated Germany’s Tatjana Maria 7-6 (5), 6-4, but fifth-seeded Coco Gauff of the U.S. was eliminated when Russia’s Anastasia Potapova took a 6-2, 6-3 decision in 77 minutes. Potapova went 6 for 6 in break points saved while Gauff managed to save 10 of 13.

No. 6 seed Elena Rybakina of Kazakhstan retired while down 6-1, 3-1 to Brazil’s Beatriz Haddad Maia.

Paula Badosa also advanced by beating fellow Spaniard Cristina Bucsa 6-1, 6-2.

–Field Level Media