Japan's Kei Nishikori won his opening match on the pre-U.S. Open hard-court circuit, beating Sam Querrey 6-4, 5-7, 6-4 in the Citi Open's second round Wednesday.

The fourth-seeded Nishikori, who received a first-round bye, was playing for the first time since losing in Wimbledon's fourth round on July 1.

Nishikori's next opponent is Lukas Lacko of Slovakia.

Two seeded men lost when Victor Estrella Burgos of the Dominican Republic beat No. 8 Feliciano Lopez of Spain 7-6 (5), 6-4, and Donald Young of the United States eliminated No. 17 Julien Benneteau of France 6-4, 6-3.

In women's action, Kristina Mladenovic of France beat American qualifier Taylor Townsend 6-3, 6-4, and Zarina Diyas of Kazakhstan stopped playing against Kurumi Nara of Japan because of a right elbow injury.