WASHINGTON — Top-seeded Dominic Thiem began his tuneup for the U.S. Open with an easy late-night victory at the rain-delayed Citi Open.

Taking the court shortly after 10 p.m. Tuesday for his opening-round match, Thiem dispatched Henri Laaksonen 6-3, 6-3, in 1 hour, 3 minutes. The Austrian dropped only eight points on his serve and one on his first serve in his first hard-court match since March.

“I felt good. It got really late. It’s always a little bit tricky after a longer period without matches,” said Thiem, a French Open semifinalist. “I’m pretty happy with my performance.”

The Citi Open also includes former champion Kei Nishikori, Milos Raonic, Grigor Dmitrov and Nick Kyrgios.

“It’s such a strong tournament,” Thiem said. “There should be basically 4 or 5 top seeds, and I’m one of them.”

Eighth-seeded Jack Sock beat Marius Copil 7-6 (2), 7-6 (6) in a match that was delayed more than 3 hours by rain.

On the women’s side, top-seeded Simona Halep defeated the 2015 Washington champion, Sloane Stephens, 7-6 (3), 6-0. Halep will face Mariana Duque-Marino in the second round. Stephens was playing her second match of the season after missing nearly a year with a stress fracture in her foot.

Halep, who reached the quarterfinals at Wimbledon, is ranked No. 2 behind Karolina Pliskova.

Ekaterina Makarova stopped Jamie Loeb 7-6 (4), 6-3, and Monica Puig beat Louisa Chirico 6-4, 6-4. The rain delay forced the women’s night matches to be postponed to Wednesday.