Swiatek, ranked No 1, will face the winner of the match between Chinese Qinwen Zheng and American wildcard Venus Williams next.

In the previous round of the Cincy Open, Collins, ranked No 34, won against Russian Anastasia Pavlyuchenkova (6-3, 6-1).

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
• Jasmine Paolini vs. Cristina Bucsa
• Petra Kvitova vs. Linda Noskova
• Qinwen Zheng vs. Venus Williams
• Petra Martic vs. Karolina Muchova: wednesday
• Maria Sakkari vs. Sorana Cirstea: wednesday
• 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)