Go Soeda reached the second round of the men's singles at the Citi Open on Monday with a straight-sets win over Darian King of Barbados.
Soeda breezed to a 6-2, 6-1 victory but Yoshihito Nishioka fell at the first hurdle when he went down 7-6 (7-1), 6-3 to Alexander Zverev of Germany.
In the women's draw, last year's runner up Kurumi Nara was knocked out in the first round, surrendering a one-set lead and going down 4-6, 6-4, 7-6 (7-4) to Kazakhstan's Yulia Putintseva.
Meanwhile in California, Misaki Doi reached the women's second round at the Bank of the West Classic with a 6-3, 7-6 (7-3) win over American Catherine Bellis.