South African Kevin Anderson and American Sam Querrey both advanced to the quarter-finals of the ATP/WTA Washington event with straight-set, second-round wins. Anderson, seeded third, on Thursday beat Florent Serra of France 6-4, 6-4, while number eight Querrey, champion last weekend in Los Angeles, reached the last eight with a win over Germany\'s Benjamin Becker 6-4, 6-3. Top seed Mardy Fish takes the court later in the day. Anderson, ranked 34th and a first-round Wimbledon loser, earned his third hardcourt win of the summer after reaching the second round last month in Atlanta. The South African punished qualifier Serra with 12 aces in their match lasting just under 90 minutes, with Anderson breaking three times and losing only one serve. He will next play Querrey, another noted big hitter who has been steadily raising his ranking this season after two years or more of injury. The Californian fired nine aces to the eight of Germany\'s Becker, with Querrey advancing on the first of three match points on a muggy day in the US capital. Querrey leads Anderson by a narrow 5-3 margin, with the US-based South African winning their last two meetings this season in Miami and Houston. The pair will play for the fourth time in 2012. In women\'s quarter-final play, Russian top seed Anastasia Pavlyuchenkova advanced over Chang Kai-chen of Taiwan 6-4, 6-4. Chang saved seven of the 10 break points she faced. Magdalena Rybarikova of Slovakia advanced to the semi-finals over compatriot Jana Cepelova 6-2, 6-4. Pavlyuchenkova said while she would have certainly been keen to compete at this week\'s London Olympic tournament, \"I\'m in this event 200 per cent.\" \"I\'m happy to be here and to play here,\" said the 21-year-old. \"I\'m a bit disappointed because the Games are so special, but I\'ll have other chances in my career.\"