The second-seeded Wozniacki breezed past Spaniard Silvia Soler-Espinosa 6-1, 6-1 just under an hour, while the third-seeded Aussie Stosur routed New Zealand´s Marina Erakovic 6-1, 6-2 on the green clay at Daniel Island Tennis Center.[break]
Wozniacki, who won here two years ago, only entered the tournament on the weekend, after she and golfer boyfriend Rory McIlroy postponed a trip to Haiti.
Stosur won here in 2010, while Wozniacki claimed the title in 2011.
"I felt like I really served well and returned well today," Wozniacki said. "Playing your first match of the year on clay, it´s always going to be difficult to slide and move unbelievably, but I felt like I did a pretty good job of that out there and I´m pleased with my work."
Stosur was playing her first match since withdrawing prior to the quarter-finals at Indian Wells in March with a calf injury.
"But as the match went on I felt really good and the way I was playing all came together," Stosur said. "And of course, I really enjoy playing on this court, so I always try to do my best every time I´m out there."
Williams, the fifth seed who won the title here in 2004, had to work harder to get past 19-year-old Puerto Rican Monica Puig.
Puig pushed the seven-time Grand Slam winner to three sets, Williams-advancing 6-2, 5-7, 6-3.
Yet another former champion was taken to the limit as seventh-seeded Jelena Jankovic, the winner here in 2007, rallied to beat French qualifier Caroline Garcia 5-7, 7-6 (12-10), 6-3.
American qualifier Mallory Burdette surprised 15th-seeded 2009 champion Sabine Lisicki 3-6, 7-6 (7/5), 7-5 in their second-round match.
Burdette booked a third-round clash with world No. 1 and reigning Charleston champ Serena Williams.
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