SINGAPORE - WTA Finals debutante Karolina Pliskova beat last year's semi-finalist Garbine Muguruza 6-2, 6-7 (7-4), 7-5 at the Singapore Indoor Stadium in a match that ended well past midnight on Tuesday morning (Oct 25).

The duo were playing the second White Group match of the BNP Paribas WTA Finals Singapore presented by SC Global.

Pliskova, the world No. 5, had to win the hard way as the Czech was down 1-4 in the third set and saved a match point en route to her victory.

She said: "It was a very tough match today and I'm very happy to be through."

Said Spain's Muguruza: "She's a very difficult opponent to play. Even though she can have a big difference in the score, with her serve and shots she can always come back.

"I'm obviously a little bit disappointed because I had my chance... but hopefully I will take it next time."

The first match of the day saw Svetlana Kuznetsova upset defending WTA Finals champion Agnieszka Radwanska 7-5, 1-6, 7-5 in a marathon that lasted two hours and 48 minutes.

Pliskova's win makes her the first debutante to win a match this year's WTA Finals, after fellow first-timers Dominika Cibulkova and Madison Keys, who are in the Red Group, lost on Sunday.

World No. 8 Cibulkova, who lost to top-ranked Angelique Kerber in three sets, will play Keys on Tuesday, while Kerber will face off against Simona Halep.