Petra Kvitova shook off a first-set loss to advance at the Western & Southern Open in Cincinnati on Monday, and Kristina Mladenovic became the first seeded player to be eliminated.
Kvitova, the No. 14 seed, beat Anett Kontaveit 1-6, 7-6 (2), 6-3. Mladenovic, seeded 13th, fell 6-0, 7-6 (6) to Daria Gavrilova.
2016 Olympic singles gold medalist Monica Puig lost to fellow qualifier Taylor Townsend 6-3, 3-6, 6-2. Roberta Vinci knocked out Timea Babos 7-5, 7-5, and Camila Giorgi ousted Katerina Siniakova 6-2, 6-2.
Beatriz Haddad Maia advanced with a 6-3, 6-2 win over Lauren Davis, and Lesia Tsurenko crafted a comeback win, defeating Anastasia Pavlyuchenkova 5-7, 7-6 (6), 6-0.
In men's play, Richard Gasquet and wild card Tommy Paul advanced in straight sets. Gasquet eased past qualifier John-Patrick Smith 6-4, 6-4, and Paul beat fellow American Donald Young 6-4, 7-6 (4).
Sam Querrey, seeded 15th, cruised into the second round with a 6-3, 6-0 win over wild card Stefan Kozlov.
Also advancing in straight sets were Fabio Fognini with a 7-6 (5), 6-4 win over Daniil Medvedev, qualifier Mitchell Krueger with a 6-2, 6-1 win over Benoit Paire, Feliciano Lopez with a 7-6 (5), 6-1 win over Hyeon Chung, and wild card Frances Tiafoe beating qualifier Maximilian Marterer 6-3, 7-6 (2).
Ivo Karlovic needed three sets to knock out Jiri Vesely 6-3, 3-6, 7-5. Qualifier Joao Sousa defeated Kyle Edmund 6-3, 2-6, 6-3.
The Associated Press contributed to this report.