SINGAPORE - World No. 5 Petra Kvitova posted her first victory at the BNP Paribas WTA Finals Singapore presented by SC Global on Wednesday afternoon, keeping alive her hopes of advancing to the semi-finals of the prestigious season finale.

She edged out No. 9 Lucie Safarova in the battle of the lefties and Fed Cup team-mates, winning 7-5, 7-5 at the Singapore Indoor Stadium.

Both Czechs have struggled with illness recently, with Kvitova down with mononucleosis and Safarova recently struck with a bacterial infection.

Said Kvitova: "It was a difficult match. I know Lucie wasn't really healthy weeks ago. I'm just happy she's here. It's great to have two Czechs here."

Both are due to play in the Fed Cup final against Russia.

Said Kvitova: "I really prefer to have her by my side, not the other side."

Safarova has yet to find a way past two-time Wimbledon champion Kvitova in eight meetings between the two. She threatened a comeback in the second set when she raced to a 3-0 lead, breaking Kvitova twice to open the set. But a slump allowed Kvitova to win the next four games, shifting the momentum to her side.

In the day's other singles tie, Garbine Muguruza, the new world No. 3, beat Angelique Kerber 6-4, 6-4 to stay undefeated in the White Group.

The results mean that all is still left to play for in the group to decide which two players progress to the semi-finals.