Russia's Anastasia Pavlyuchenkova was made to fight for a place in the second round of the St. Petersburg Ladies Trophy on Tuesday, beating Czech veteran Klara Koukalova in three sets.

World No. 26 Pavlyuchenkova, who is seeded fifth in St. Petersburg, needed 2 hours, 14 minutes to beat qualifier Koukalova 6-4, 4-6, 6-4. Her reward is a second-round meeting with German Carina Witthoeft, who defeated Austrian Tamira Paszek 6-3, 6-3.

Monica Niculescu of Romania, the world No. 37, moved into the second round earlier in the day with a 6-0, 6-3 win over Russia's Natalia Vikhlyantseva.

Niculescu, seeded ninth, broke the 265th-ranked Russian teenager in the eighth game of the second set to go up 5-3, then held serve for the win in the Sibur Arena in St. Petersburg.

Niculescu's opponent in the second round will be Hungary's Timea Babos.

Barbora Strycova of the Czech Republic was playing in her first tournament since a strong run at the Australian Open saw her beat Garbine Muguruza, but was out of sorts Tuesday, falling 6-3, 6-4 in the first round against Ukrainian qualifier Kateryna Kozlova.

Top-seeded Belinda Bencic of Switzerland had a bye in the first round as did the next three seeded players: Roberta Vinci of Italy, Caroline Wozniacki of Denmark and Ana Ivanovic of Serbia.

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(This story has been corrected to show the last name of the player is Ivanovic, not Ivanovich.)