CHARLESTON, S.C. -- Teenager Daria Kasatkina doesn't just upset the top-ranked player in the world. She can also win a tournament.
The 19-year-old Russian showed patience and poise Sunday to beat fellow teen Jalena Ostapenko to win her first WTA event at the Volvo Car Open.
It was the first final between two teens on the WTA tour in eight years. Kasatkina, playing in her first final, handled the pressure better, letting her Latvian opponent make mistakes.
She broke Ostapenko in five of her last six service games, including Ostapenko's last game on serve when she made three straight unforced errors to lose the game without a point.
"I got back, I spinned the ball, running and everything,'' Kasatkina said.
A rising star on tour, Kasatkina twice beat top-ranked Angelique Kerber this season. But this one meant a lot more.
Kasatkina dropped to her knees after Ostapenko's return went wide on match point and wiped tears from her eyes as she hugged her brother and her coach Vladimir Platenik.
"I'm just enjoying every moment, every second. When I was on the court after the last point, I just wanted the moment to stop,'' Kasatkina said.
The teen said she would celebrate in Charleston before catching her early Monday flight to Russia. Her eyes got big when she was told as the defending champion, her picture will hang on the side of the stadium for the next year.
Kasatkina thanked her coach and said he helped turn things around after she lost openers in three straight tournaments after beating Kerber in the second round of the Qatar Total Open in February.
"I lose all this confidence because I am losing every tournament,'' Kasatkina said. "But hard work pays off.''
Ostapenko said she was pleased with her tournament overall. It was only her third WTA final and her first on clay. But she said she was tired after playing both the semifinals in singles and doubles on Saturday.
"She was trying to play defensive -- play slice, play lobs and to keep serve -- to try everything to make me uncomfortable,'' Ostapenko said. "Normally, I'm fine with that, but today, I just did not feel the ball that well.''
Kasatkina's win ended a tournament that featured upsets. It's the first time since 2002 that none of the 16 seeded players made it to the finals in Charleston.
Top-seeded Bethanie Mattek-Sands of the United States and Lucie Safarova of the Czech Republic won the doubles title over the Czech team of Lucie Hradecka and Katerina Siniakova, winning the super tiebreaker 10-7 after each team split a set.