NEW YORK — Serena Williams didn’t drop a game in advancing to the quarterfinals of the US Open.
Roger Federer moved on with even less work when Mardy Fish pulled out of their fourth-round match Monday for precautionary reasons.
Fish missed about two months this season because of an accelerated heartbeat and had a medical procedure in May. His agent, John Tobias, said, ‘‘We are not 100 percent sure what the issue is and if it is related to his previous issues.’’
‘‘I was reluctant to do so, but am following medical advisement,’’ Fish said about his withdrawal in a statement. ‘‘I had a good summer and look forward to resuming my tournament schedule in the fall.’’
The 30-year-old American’s third-round match against Gilles Simon went five sets, lasting more than three hours and ending after 1 a.m. Sunday. Afterward, the 23d-seeded Fish did not appear at a news conference. Tournament officials said he was getting treatment, but didn’t give specifics.
‘‘I am really sorry for Mardy. I just want to wish him a speedy recovery,’’ Federer said in a statement. ‘‘We all want to see him back on tour soon.’’
Fish’s departure means 2003 champion Andy Roddick is the only American man left in the field. Roddick, who announced last week that he'll retire after the US Open, plays 2009 champion Juan Martin del Potro in the fourth round Tuesday night.
Williams beat 82d-ranked Andrea Hlavackova, 6-0, 6-0, in 57 minutes. It was the first time in 62 victories at Flushing Meadows that the three-time US Open champion enjoyed a ‘‘double bagel.’’
‘‘She was fighting really hard,’’ Williams said. ‘‘You give people any type of chance, especially in tennis, the match is never over until you shake hands. There is always a comeback available. So I didn’t want to give her that opportunity — or anyone that opportunity — to try to come back, especially her in particular. She was getting so pumped up and she never gave up. I thought that was really incredibly positive.’’
Williams had 31 winners and just seven unforced errors.
Hlavackova, a 2011 French Open doubles champion, had never been past the second round in singles at a major tournament before this year.
Serena and sister Venus Williams later lost in the third round of doubles, falling, 6-1, 6-4, to the fourth-seeded Russian pair of Maria Kirilenko and Nadia Petrova.
The sisters were seeking their 14th Grand Slam doubles title.
Monday’s defeat ended Venus Williams’s US Open. She lost in the second round of singles.
Serena Williams will next face Ana Ivanovic, who is finally back in a Grand Slam quarterfinal more than four years after her French Open title.
The 12th-seeded Serb beat Tsvetana Pironkova, 6-0, 6-4. Ranked No. 1 in the world in 2008, Ivanovic has struggled with injuries and her confidence since.
‘‘There were some good moments and some tough ones, but it’s a process. I understand it better now,’’ she said. ‘‘There are times when you realize that it’s exactly what it is: It’s a process. You can’t have everything at the same time. You have to be consistent on practice courts and then in the matches.’’
After failing to serve out the match at 5-3 in the second set, Ivanovic broke the 55th-ranked Bulgarian at love in the next game to clinch the victory.
Federer, in his 34th consecutive quarterfinal at a major tournament, will meet sixth-seeded Tomas Berdych, who defeated 11th-seeded Nicolas Almagro, 7-6 (6-4), 6-4, 6-1.
Andy Murray muted 15th-seeded Milos Raonic’s big serve and won, 6-4, 6-4, 6-2, to reach his eighth consecutive major quarterfinal.
Murray, seeded third, will play No. 12 Marin Cilic, who put together a 7-5, 6-4, 6-0 victory over Martin Klizan.
Italian doubles partners Sara Errani and Roberta Vinci each won to set up a meeting in the quarterfinals. Vinci upset second-seeded Agnieszka Radwanska, 6-1, 6-4.
In men’s doubles action, Bob Bryan saved a key point in a second-set tiebreaker by hitting a shot through his legs, then he and his brother, Mike, went on for a 6-7 (8-10), 7-6 (7-5), 6-3 victory over Scott Lipsky and Santiago Gonzalez in the third round.
The Bryan brothers are in search of their 12th Grand Slam title and fourth at Flushing Meadows.
Tied at 5 in the second-set tiebreaker, Bob Bryan was facing the net when a shot came directly toward his midsection. He stuck the racket behind him and between his legs to knock it back, then followed with an acutely angled forehand winner.