Second seed Caroline Wozniacki beat fourth seed Petra Kvitova 7-5, 3-6, 6-2 in their second white group round-robin match at the WTA Finals in Singapore. But the defending champion's victory in almost two-and-a-half hours improved her chances of qualifying for the knockout stage. But world number three Wozniacki played steadier defence and waited for the Czech to make mistakes. Wozniacki, who broke her opponent in the first and fifth games of the deciding set, took a medical timeout to have her left knee bandaged when Kvitova was leading 3-1 in the second. World number five Kvitova finished the match with 40 winners and 40 unforced errors, while Wozniacki had 19 winners and 14 unforced errors.