Caroline Wozniacki came out on top in a pulsating battle with Karolina Pliskova to reach the decider of the WTA Finals and ensure Simona Halep will end the year at the top of the rankings.

Sixth seed Wozniacki will face Caroline Garcia or Venus Williams in her second WTA Finals showdown on Sunday after beating Pliskova 7-6 (11-9) 6-3 in a high-quality first semi-final in Singapore.

The Dane saved six set points before winning a marathon opening set in a tie-break and broke three times in the second to dump the third seed out.

Pliskova needed to win the title to usurp Halep, but it is the Romanian who will end the year as world number one despite failing to progress to the last four of the season-ending tournament.