Charleston: Reigning US Open champion Samantha Stosur put the latest match-up in the Williams sisters' sibling rivalry on hold by rallying past Venus Williams at the Family Circle Cup. The second-seeded Stosur won five of the last six games for a 6-3, 4-6, 6-3 victory in the quarter-finals on a chilly, windy Friday at the season's first clay-court event. Stosur now has a chance at knocking out both Williams sisters on consecutive days when she meets Serena in Saturday's semi-finals.While Stosur had never beaten Venus Williams before, she's had success against Serena. Stosur beat her to win the US Open title last September and won their only match on clay in the 2010 French Open quarters."For sure, clay's not my favorite surface," said Stosur, the 2010 Family Circle champion. "It's always tough playing Serena no matter where."Serena Williams advanced when Sabine Lisicki twisted her left ankle early in the opening set and had to withdraw after five games.The buzz for a Williams' sisters showdown had grown all week as the two Americans moved through the draw. Both came into Friday without losing a set and appeared ready to settle some family business at the Family Circle Tennis Center.This was Venus Williams' first clay-court tournament since 2010 and her second event since a bout with the autoimmune disease Sjogren's Syndrome kept her out of the game since last summer's US Open. Williams won four times last week at the Sony Ericsson Open and had carried that success into the Family Circle quarters. She could not get past Stosur, though, and won't play again until next month in Madrid."I have come so far, so far from the US Open," Venus Williams said.Stosur shook off some tired legs from an earlier match â the Australian was forced to come back Friday morning and finish her rain-delayed match from the night before â and some wayward serves midway through while moving past Williams.Stosur is seeking her second Family Circle Cup title in three years.Stosur came out fast for a 5-2 lead in the opening set. Williams mishit Stosur's 113 mph serve on set point. That's when Stosur's own service game began to fall apart. She struggled to get the ball in play and Williams took full advantage of Stosur's slower second serves. Stosur had the chance to go up 3-1 in the set, but sent a forehand wide. Venus Williams eventually won to tie the set at 2-all and closed it out by winning four of the next six games.Williams carried the momentum â along with the support of the crowd â into the final set and held serve to lead 2-1. Stosur, though, regained her accuracy and Williams began to tire. Stosur only lost two points over the final two games. Willilams slowly walked to the net after her service return went wide on match point."I did my best," Venus said. "I know I can play even better. My errors didn't help my cause. At this point, I'm just learning and learning and learning more."Williams is schedule to play in Madrid, Rome and the French Open as she strives to make the US Olympic team for the London Games this summer. She said her plan was to head home, practice and get stronger for the competition ahead.She has risen about 60 spots in the rankings from 134th before Key Biscayne to now. "I've never been so happy to be 70th in the world," Williams said.Early on, it looked as if Serena Williams might have a fight on her hands as Lisicki stood toe-to-toe with the 13-time Grand Slam winner. However, as Lisicki moved to her left after a shot, she apparently hurt her left ankle and fell to the court. She immediately got up and called for the trainer, who re-taped her ankle so the 22-year-old German could continue.It was obvious Lisicki couldn't move as she had. She played three more games before retiring in tears. Serena Williams came over to console Lisicki, hugging her near the net and applauding along with the crowd as she left stadium court.Lisicki was having an MRI. "We'll see what the doctors say and we'll go from there," she said.Williams has had her share of injuries that forced her to miss major tournaments. She told the young German that she had time to heal and would be back."I said, 'It's OK. It's not the French Open. You've got time to get better,'" Williams said.Ninth-seeded Lucie Safarova ousted No. 4 seed Vera Zvonareva, 6-3, 6-3. Safarova will meet No. 14 seed Polona Hercog in the semi-finals. Hercog defeated 13th-seeded Nadia Petrova 6-1, 6-2.