WASHINGTON (AP) -- Mardy Fish knows what he'd have to do for his ankle to heal. He's just not interested in doing it.
Still feeling the effects of a right ankle injury sustained two weeks ago in Atlanta, the top-seeded American beat Ricardas Berankis 6-3, 6-1 on Thursday night to advance to the Citi Open quarterfinals.
Fish said the injury doesn't hamper his movement, and he can play through the discomfort.
"That's a tough thing, because it needs rest and I'm just not going to give it rest,'' Fish said. "I can't give it rest. I'm not going to miss these tournaments.''
Fish already missed time this year after he underwent a heart procedure in May to correct an arrhythmia. Now he's more concerned about regaining his match fitness than about his ankle.
"I need matches,'' he said. "I need to play.''
Fish will face Xavier Malisse on Friday. Malisse beat sixth-seeded Jeremy Chardy 6-3, 6-2.
The No. 13-ranked Fish knows he isn't at top form, but he also believes he's not too far away.
"I feel like I can go out against someone like I played tonight and not lose,'' he said. "That's important. You'd be surprised, in years past I felt like I could really beat anyone, but I could also lose to anyone on any given day. And I feel like if I play relatively normal right now - I have the confidence, anyway, it might not be true - I have the confidence that I don't lose many matches like that anymore.''
Eighth-seeded Sam Querrey also advanced, finishing off Benjamin Becker with his eighth ace of the match in a 6-4, 6-3 victory.
Querrey, the Farmers Classic winner in Los Angeles on Sunday for his first title of the year, won all 24 of his first-serve points and on 22 of Becker's 33 second serves.
"I thought I returned really well,'' Querrey said. "Especially on his second serves I was really aggressive, more so than normal, and it paid off,''
Querrey will face third-seeded Kevin Anderson, a 6-4, 6-4 winner over Florent Serra.
In the women's tournament, top-seeded Anastasia Pavlyuchenkova advanced to semifinals, beating Kai-Chen Chang 6-4, 6-4. Pavlyuchenkova was broken early and fell behind 4-1 before rallying to set up her first semifinal match of the year.
"It wasn't my best match today at all,'' Pavlyuchenkova said. "She went out there and was playing really well. I kept going, and I kept trying to find my energy. I'm happy I pulled it out.''
The Russian reached the quarterfinals of the French Open and US Open in 2011, but struggled for much of this year. She reached the quarterfinals in Bastad, Sweden, in her last event.
"Now there's a huge difference and I feel my game is much better than it was two weeks ago,'' she said. "Maybe it's just my mentality that I'm much more aggressive here.''
Fourth-seeded Vania King beat No. 7 Coco Vandeweghe 6-1, 3-6, 6-4. King broke Vandeweghe twice to take the first five games, and finished off the third set by breaking Vandeweghe for the fourth time.
"She has a lot more power than I do,'' King said. "I just hung in there and tried to be aggressive when I could and tried to take my chances when I could.''
King will play Pavlyuchenkova in the semifinals Friday. King has won the last three matchups between the two.
"She's also a big, strong player,'' King said. "She doesn't want to play long rallies, I know that for sure, and it'll be up to me to be solid enough to beat her.''
Magdalena Rybarikova advanced to the other semifinal with a 6-2, 6-4 victory over qualifier Jana Cepelova. She'll play third-seeded Sloane Stephens, a 6-4, 6-4 winner over Eugenie Bouchard.