Terra

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Serena Williams didn't drop a game in advancing to the quarterfinals of the U.S. Open.

Roger Federer moved on with even less work when Mardy Fish pulled out of their fourth-round match Monday for precautionary reasons.

Williams beat 82nd-ranked Andrea Hlavackova 6-0, 6-0 in 57 minutes. It was the first time in 62 career victories at Flushing Meadows that the three-time U.S. 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. She and sister Venus play doubles during Monday's night session in Arthur Ashe Stadium.

Hlavackova, a 2011 French Open doubles champion, had never been past the second round in singles at a major tournament before this year.

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.

Sara Errani, seeded 10th, beat sixth-seeded Angelique Kerber 7-6 (5), 6-3.

Federer, in his 34th consecutive quarterfinal at a major tournament, will meet sixth-seeded Tomas Berdych, who defeated 11th-seeded Nicolas Almagro 7-6 (4), 6-4, 6-1 in 2 hours.

"At least good that I didn't stay that long on court, that I was able to save some energy, as well," Berdych said.