Top seed Julia Goerges is out of the Moscow River Cup after losing to Olga Danilovic in the quarterfinals.
Georges, the world No. 10, was the tournament favorite but Danilovic,17, played the match of her life, sealing the upset with a straight-sets 6-3, 6-3 victory.
“Every win here is important, especially since I played with one of the top players in the world right now,” Danilovic told the WTA website. “It’s an amazing feeling, an amazing win.”
This was the Serbian’s first win over a WTA top-10 opponent, after only qualifying to the main draw as the lucky loser.
Danilovic now advances to her first WTA semifinal and will face Aliaksandra Sasnovich, the last remaining seed, who had a walkover win against the injured Anastasija Sevastova.
Elsewhere, Russian Anastasia Potapova came from a set down to defeat Valentyna Ivakhnenko 1-6, 6-3, 6-2.
She will now play Tamara Zidansek in the other semifinal Saturday after she beat Laura Siegemund 6-3, 6-4.