Jelena Ostapenko
Ostapenko also becomes the first Latvian to reach a grand slam final. Reuters

Jelena Ostapenko has become the first unseeded player in 34 years to reach the French Open final after seeing off Timea Bacsinszky in a pulsating clash in Paris.

Ostapenko booked her place in Saturday's final with a 7-6 (7-4) 3-6 6-3 over the world number nine, becoming the first ever Latvian player to reach a grand slam final.

Both Ostapenko and the Swiss Bacsinszky, aged 28, were celebrating their birthdays as they met on court on Thursday but the former will be the only one celebrating tonight after becoming the first player since Mima Jausovec in 1983 to book her place in the final of one of tennis' four majors as an unseeded entry.

She will meet Simona Halep in Saturday's final after the Romanian sealed a 6-4 3-6 6-3 win over Karolína Plíšková.

In a fearless display, Ostapenko fought back after an early break to take the opening set, although she was almost blown off course in the second, surrendering four straight games and allowing Bacsinszky to draw level.

Neither woman able to hold serve in the third but at 3-3, Ostapenko summoned the resolve to keep her opponent out, winning the next three games to book a historic final.

"I always play aggressive and I was always trying to hit the ball when I had a chance. That helped me win today," Ostapenko said.

"I love playing here, thanks for coming, I'm just happy with the way I celebrated my birthday."

She will meet Halep in the final after the 25-year-old Romanian secured a 6-4 3-6 6-3 victory over Plíšková. After a disappointing first set where she made 24 unforced errors, Plíšková saw off three break points to clinch the second with a vicious forehand winner on her second set point, forcing a deciding third.

Despite that fightback, the Czech ran out of steam after being broken midway through the third and couldn't keep pace with Halep who booked her second Roland Garros final.