Seventh seed Polona Hercog and outsider Mandy Minella will contest the inaugural Bol Open final on Sunday.
World number 186 Minella is just one victory away from claiming her first WTA singles title after Ana Konjuh retired from Saturday's semi-final due to a lower back injury when trailing 6-2 2-1.
Croatian teenager Konjuh was eyeing a second tournament victory at the age of 18, but her run came to an end at the semi-final stage on home soil.
"I'm sorry for the fans and I'm sorry for the tournament," Konjuh told Croatian media after the match. "I tried to go on but today it didn't work. I hope it will not be anything serious."
Seventh seed Hercog eased to an emphatic 6-0 6-2 victory against Japanese fourth seed Nao Hibino in just 61 minutes.
The 94-ranked Slovenian will end a four-year wait for a title if she gets the better of Minella.