Elina Svitolina of Ukraine hits a return shot to Karolina Pliskova of the Czech Republic during their WTA Finals Tennis Tournament in Shenzhen, China's Guangdong province, Monday, Oct. 28, 2019. (AP Photo/Andy Wong)

SHENZHEN, China (AP) — Defending champion Elina Svitolina stretched her unbeaten run at the WTA Finals into a new year, beating Karolina Pliskova 7-6 (12), 6-4 in her opening match Monday at the season-ending tournament.

Svitolina, the only player in this year’s field who has not won a title this season, was unbeaten in the tournament last year.

After exchanging service breaks in the first set, Svitolina converted her seventh set point. Pliskova also had a chance to take the first set, but she failed to take advantage of a set point at 9-8 in the tiebreaker.

Svitolina then jumped ahead 2-0 in the second set and then broke again for a 4-3 lead.

The victory gives Svitolina a 1-0 record in the Purple Group, while Pliskova is 0-1.

Pliskova, who had won all three of her previous opening matches at the WTA Finals, leads the tour with four titles this season — winning in Brisbane, Rome, Eastbourne and Zhengzhou. She also leads the tour with most aces served at 481.

Wimbledon champion Simona Halep and U.S. Open champion Bianca Andreescu will play in the second singles match on Monday. (AP)