MONTERREY, Mexico, March 4 (UPI) -- Li Na backed up her first-round upset Wednesday by downing Petra Cetkovska in the second round of the inaugural Monterrey Open.
Li shocked Agnieszka Radwanska, the world's 10th-ranked player, with a three-set triumph in the opening round and then defeated Cetkovska 6-3, 6-4.
Another Chinese player, fourth-seeded Jie Zheng, moved into the quarterfinals Wednesday with a 6-3, 6-4 decision over Melinda Czink. No. 7 seed Gisela Dulko ousted Mariya Koryttseva 6-2, 6-4.
In another second-round match at the Sierra Madre Tennis Club, Lucie Safarova advanced when eight-seeded Maria Kirilenko retired with an inflamed left knee. Safarova was leading at the time 6-4, 4-1.