Miami (AFP) - Russia's Daria Kasatkina came up trumps in her first WTA final on Sunday, breezing past fellow 19-year-old Jelena Ostapenko 6-3, 6-1 to claim her maiden title in Charleston.

"It's very difficult to describe my feeling now," Kasatkina said. "I feel I'm just sleeping and everything is not real. I'm so happy."

In the first all-teen WTA final since 2009, Kasatkina's consistency paid off.

She belted just seven winners to her Latvian opponent's 25, but she also made just seven unforced errors to Ostapenko's 38.

They traded breaks early in the opening set, Ostapenko levelling the set at 3-3 before Kasatkina ruthlessly pulled away to win in just 66 minutes.

"Yesterday evening and all night I couldn't sleep," Kasatkina said.

"I woke up during the whole night like two or three times. I was so nervous, you cannot imagine. I was feeling like, I want to just go on the court and everything let's finish, play. I cannot (stand) feeling this anymore. But now it was worth it."

The two players have a long history in the junior ranks, but had met just once before at the WTA level, when Ostapenko triumphed last year at Eastbourne.

The 42nd-ranked Kasatkina is now slated to return to the top 30 on Monday as she aims to return to Roland Garros as a seeded player for the second straight year.

Ostapenko, now 0-3 in finals after defeats in Quebec in 2015 and at Doha last year, will rise from 66th in the world back into the top 50.

But she will regret a final she called her "worst match" of a week that included victories over former world No. 1 Caroline Wozniacki and 2017 Australian Open semi-finalist Mirjana Lucic-Baroni.

Kasatkina, whose victory underscores her rising-star status already established with two wins over world No. 1 Angelique Kerber this year, became the sixth teenager to lift the Charleston trophy - a list that also includes Chris Evert, Tracy Austin, Steffi Graf, Martina Hingis and Sabine Lisicki.