Sakkari, ranked No 8, will play the winner of the match between Croat Petra Martic and Karolina Muchova next.

In the previous round of the Cincy Open, Cirstea, ranked No 31, won against Russian Ekaterina Alexandrova (6-0, 6-2).

Cincinnati WTA 1000, other first-round results (Linder Tennis Family Center, hard, USD 2.788.468, most recent results first):

• Mayar Sherif vs. Coco Gauff
• Ann Li vs. Aryna Sabalenka
• Donna Vekic vs. Victoria Azarenka
• Elise Mertens vs. Marie Bouzkova
• Elena Rybakina vs. Jelena Ostapenko
• Petra Kvitova vs. Linda Noskova
• Jasmine Paolini vs. Cristina Bucsa
• Qinwen Zheng vs. Venus Williams: wednesday
• Petra Martic vs. Karolina Muchova: wednesday
• Iga Swiatek (1) beat Danielle Collins (WC): 6-1, 6-0
• Marketa Vondrousova (10) beat Anastasia Potapova: 6-4, 6-2
• Jessica Pegula (3) beat Martina Trevisan (Q): 6-7 (2), 6-2, 6-3
• Daria Kasatkina (14) beat Varvara Gracheva (LL): 6-3, 6-1
• Sloane Stephens beat Caroline Garcia (6): 4-6, 6-4, 6-4
• Ons Jabeur (5) beat Anhelina Kalinina: 6-3, 6-7 (2), 7-6 (2)