Marin Cilic, the reigning United States Open champion, reached the semifinals of the Citi Open in Washington by beating Alexander Zverev, 7-5, 7-6 (3). He will face Kei Nishikori, a 6-4, 6-4 winner over Sam Groth, in a rematch of last year’s U.S. Open final.
In the women’s quarterfinals, Sam Stosur advanced when Monica Niculescu stopped playing because of a left abdominal strain while trailing, 4-0. Stosur will face Sloane Stephens, who defeated Louisa Chirico, 6-4, 6-4.
u25a0 Karolina Pliskova advanced to the Bank of the West Classic semifinals in Stanford, Calif., beating Ajla Tomljanovic, 6-2, 6-4.