NEW YORK — Serena Williams didn't drop a game Monday as she moved into the quarterfinals of the US Open. Serena Williams was just as ruthless as she charged into the women's quarters with a 6-0, 6-0 win over Czech Andrea Hlavackova. Showing no mercy against her 82nd ranked opponent, Williams sent an ominous warning of her intention to add the US Open title to her recent wins at Wimbledon and the London Olympics with a rare ‘double bagel' victory in 57 minutes. “Andrea played really well today even though it was love and love,” Williams said in a courtside interview. “I think I played really well today. I haven't played like that all tournament.” “The first point of the whole match,” Hlavackova explained, “when I served, and she returned, like, a 100 mph forehand return, I was like, ‘OK, I know who I'm playing. You don't have to prove it to me. I know.'” Hlavackova, a 2011 French Open doubles champion, had never been past the second round in singles at a major tournament before this year. Williams's next opponent is Serbia's Ana Ivanovic, a former world No. 1 who has rediscovered her best after a lean few years where she struggled with injuries. “She's obviously a great player and she's been playing the best out of all the girls on tour at the moment,” said Ivanovic. “Her serve is definitely her strength. I really have to be sharp from the first moment on and stay aggressive and stay in the moment.” Andy Murray produced a masterclass in tennis to destroy the highly rated Milos Raonic Monday and book his place in the quarterfinals of the US Open. The Olympic champion blunted one of the biggest serves in the game to win 6-4, 6-4, 6-2. Poland's Agnieszka Radwanska, the women's second seed, became the highest ranked casualty of the tournament when she lost to Roberta Vinci 6-1, 6-4. The Italian will now play doubles partner and best friend Sara Errani after she upset Germany's Angelique Kerber 7-6, 6-3. Croatia's big-serving Marin Cilic defeated Slovakia's Martin Klizan 7-5, 6-4, 6-0 to secure a place against Murray, who cruised to victory in two hours. Russian duo get revenge on Williams sisters Russians Nadia Petrova and Maria Kirilenko avenged a pair of stinging London defeats by beating Venus and Serena Williams in the women's doubles Monday. Petrova and Kirilenko claimed a 6-1, 6-4 victory on Louis Armstrong Stadium court for their first victory over the American sisters, to reach the quarter-finals. The Williamses beat the Russians 3-6, 6-3, 9-7 in the second round at the Wimbledon championships after Kirilenko and Petrova had led 4-1 in the third set in their first meeting. The Americans went on to claim their 13th grand slam doubles title. Serena and Venus then returned to the All England Club and beat the Russian pair 7-5, 6-4 in the Olympic semifinals before going on to claim their third gold medal together. “It feels great,” said Kirilenko. “It was a good victory for us,” added Petrova. The Russians said playing on the Flushing Meadows hard court rather than London grass had made a difference, giving them a better chance at returning serve and getting into the points. Petrova and Kirilenko were virtually immaculate with their groundstrokes, committing only three unforced errors in the match. “We played clean tennis, very consistent,” said Petrova, who was coming off a three-set loss to Maria Sharapova in the fourth round of singles. Petrova said it was good to come back the next day and win. “Especially against the Williams sisters,” Kirilenko quickly added. Mardy Fish pulled out of the fourth-round match against Roger Federer for precautionary reasons. Fish missed about two months this season because of an accelerated heartbeat and had a medical procedure in May. Fish's agent said he wasn't sure if the problem related to his previous health 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 3 hours and ending after 1 A.M. Sunday. Afterward, the 23rd-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.” — Agencies