Fourth-seeded Alexandra Dulgheru of Romania and No. 7-seeded Mathilde Johansson of France were knocked out in the first round of the Monterrery Open on Tuesday.
Dulgheru was beaten by Silvia Soler-Espinosa of Spain 6-3, 6-3, and Mathilde Jonansson lost to Mandy Minella of Luxembourg 6-1, 5-7, 7-6 (5).
Other seeded players fared better in the outdoor, hard-court event.
No. 6-seeded Greta Arn of Hungary beat Zhang Shuai of China 6-1, 6-4, and eighth-seeded Lourdes Dominguez Lino of Spain defeated Monica Puig of Puerto Rico 6-3, 6-3.
Other first-round winners included Frenchwoman Alize Cornet, Maria Abramovic of Croatia, Yaroslava Shvedova of Kazakhstan, Valeria Savinykh of Russia and Hungary's Timea Babos.