Fifth-seeded Fręch, currently ranked No. 24 in the world, defeated Ukraine’s Julia Starodubtseva in straight sets, 6–2, 6–4.
Linette, seeded eighth and ranked No. 28, ousted American Danielle Collins 7–5, 6–4 in a tight contest, Polish state news agency PAP reported.
Both Poles must wait to learn their next opponents.
Fręch could face seven-time Grand Slam singles champion Venus Williams, who entered the tournament as a wild card. The 44-year-old American, a former world No. 1, is set to play countrywoman Peyton Stearns in the first round on Tuesday.
Linette’s next opponent will be the winner of an all-Russian matchup between 48th-ranked Anna Kalinskaya, a 2019 semifinalist in Washington, and qualifier Kamilla Rakhimova.
The 2025 Washington Open, also known as the DC Open, runs until Sunday.
(gs)
Source: IAR, PAP