ST. PETERSBURG, Russia — Daria Kasatkina won the St. Petersburg Ladies Trophy on Sunday when wild card Margarita Gasparyan retired from their all-Russian final with a lower back injury.

The eighth-seeded Kasatkina was leading 6-3, 2-1 when Gasparyan’s back problems forced her to retire.

Kasatkina became the first player to win two WTA tournaments this year after winning in Melbourne, Australia last month. It’s her fourth title overall.

More AP tennis: https://apnews.com/hub/tennis and https://twitter.com/AP_Sports