Benesova will meet 20-year-old Slovakian Magdalena Rybarikova for a spot in the final.
"It's important for me to win a few matches at the beginning of the season," Benesova said. "My game is going pretty good so far -- the semis here is not bad -- we'll see if it can be better."
Ranked 43rd at the end of 2008, Benesova is the highest-ranked player remaining in the tournament after all the seeded players were ousted in the first two rounds.
She will meet France's Virginie Razzano, who beat Bulgaria's Tsvetana Pironkova 6-4, 6-1.