Third-seeded Taylor Fritz of the United States retired in the third set on Thursday due to illness in searing conditions in Washington, allowing 16th-seeded Daniel Evans of Great Britain to advance to the quarterfinals of the Citi Open.
Evans led 3–6, 7–6 (6), 4–1 when Fritz halted the match.
Fritz later wrote in a social-media post, "Today I constantly felt like I was going to pass out, my vision was going fuzzy."
He added that he wasn't prepared for such conditions because his recent training was curtailed due to a foot injury, but that the foot held up fine on Thursday.
Evans' quarterfinal foe will be Japan's Yoshihito Nishioka, who upset seventh-seeded Karen Khachanov of Russia 7–6 (2), 7–6 (1).
In the only other third-round match that was completed, Sweden's Mikael Ymer defeated Finland's Emil Ruusuvuori 6–3, 6–7 (3), 6–4.
Abierto de Tenis MifelTop-seeded Daniil Medvedev of Russia needed just 80 minutes to cruise past Lithuania's Ricardas Berankis 62, 6–2 in the quarterfinals at Los Cabos, Mexico.
Medvedev finished with an 8–1 edge in aces and won 88 percent of his first-serve points. Next up for Medvedev is a meeting with fourth-seeded Miomir Kecmanovic of Serbia, who routed sixth-seeded Brandon Nakashima 6–2, 6–4.Two matches were scheduled for later Thursday, with second-seeded Felix Auger-Aliassime of Canada facing the United States' Steve Johnson while third-seeded Cameron Norrie of Great Britain opposing Radu Albot of Moldova.