CHARLESTON, South Carolina — Ex-champions Sam Stosur and Caroline Wozniacki cruised into the third round of the WTA Tour's Family Circle Cup Wednesday, while Venus Williams had to battle her way through. 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. 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 quarterfinals 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. Venus Williams fought through a second-set lull to rally past Puig in their first-ever meeting. Williams withdrew from the Sony Open with a bad back and said it was difficult to feel 100 percent less than two weeks later. “It's hard to be all the way prepared, but at that point, it's about being mentally tough,” Venus Williams said. “It's good to start off with a win.” 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. — Agencies