Samantha Stosur and Vera Zvonareva claimed the last two spots in the semifinals of the TEB BNP Paribas WTA Championships in Friday\'s final round-robin matches. Stosur qualified from the White Group with a 6-1, 6-0 rout of Li Na. Zvonareva was inserted as the second Red Group semifinalist when Petra Kvitova rallied to beat Agnieszka Radwanska 7-6 (7-4), 6-3 in Istanbul, Turkey. Marion Bartoli, filling in for the injured Maria Sharapova, kept Victoria Azarenka on the court for more than 2 1/2 hours in taking a 5-7, 6-4, 6-4 decision in the final match of group play. How that affects Azarenka remains to be seen in her semifinal match Saturday against Zvonareva, who didn\'t play Friday. The first semifinal has Stosur going against Kvitova. Radwanska only needed to win one set against Kvitova to advance to Saturday\'s semis and seemed on the verge of doing that by jumping out to 5-1 lead and serving for the first set. But Kvitova, who had already secured a place in the semis, broke Radwanska\'s serve at 15, setting off a string of four straight wins. Kvitova also won the first four points in the tiebreaker. Kvitova claimed an 18-point game, in which Radwanska had three break chances, and then broke Radwanska at love for a 5-3 edge in the second set. Stosur improved to 6-0 lifetime vs. Li with an easy 66-minute win. Stosur won nearly two-thirds of the points and recorded breaks all six times Li served. Top seeds Caroline Wozniacki and Sharapova were the first players eliminated in group play. Wozniacki, however, still assured herself of the world No. 1 year-end ranking. Kvitova (3-0) won the Red Group with Zvonareva, Radwanska and Wozniacki all 1-2. Azarenka wound up 2-1 with Stosur 2-1, Li 1-2 and Sharapova 0-2 in White Group play.