Youngsters set for WTA Charleston final

Daria Kasatkina of Russia and Jalena Ostapenko will play in the final of the WTA event in Charleston.

Daria Kasatkina (pic) and Jalena Ostapenko will play in the final of the WTA event in Charleston. (AAP)

Unseeded Daria Kasatkina of Russia and Latvia's Jalena Ostapenko each moved into position for their first WTA title, with semi-final wins in Charleston.

Kasatkina rallied from a set down to beat Laura Siegemund 3-6 6-2 6-1 and Ostapenko held off the tournament's lone remaining seed in No.11 Mirjana Lucic-Baroni, 6-3 5-7 6-4.

Neither Kasatkina, 19, nor Ostapenko, also 19, have won a WTA title and will be seeking the first of their careers when they play in Sunday's (Monday AEST) final.

Kasatkina played sluggishly early against Siegemund before rallying to win 12 of the final 15 games.

Ostapenko took the third set from Lucic-Baroni to advance.

Ostapenko moved into the semis when fifth-seeded Caroline Wozniacki withdrew in the second set of Friday's match.