Spurred on by the vocal support of her coaching group on Court Philippe Chatrier, the 85th-ranked Zidansek conquered Spanish rival Paula Badosa 7-5, 4-6, 8-6 Tuesday at the clay-court championship.
"It feels overpowering," she explained.
The French Open is the only remaining Grand Slam in which tiebreakers are not played in the last set. Wimbledon recently installed tiebreakers at 12-12 at the last set.
After splitting the first two sets, Badosa violently threw her racket in anger in the changeover after Zidansek held for a 6-5 lead at the third. She regained her composure but Zidansek then saved three break points to take a 7-6 lead and transformed her second match point with a huge forehand within the next match.
Zidansek, a three-time national junior ski winner in Slovenia, will face either Elena Rybakina or Anastasia Pavlyuchenkova to get a spot in the final at Roland Garros.
In perfect weather conditions, the two players pulled off some spectacular winners but also hit a lot of unforced errors. Badosa, who was among the six girls in the quarterfinals at a major for the first time, stated she had been too nervous.
"I did not feel myself at the entire game," she explained. "I am a little bit sad about that, since I think I played with possibly the worst game of the tournament as well as the clay season, but occasionally it's like that."
Badosa applied pressure from the start with a flurry deep groundstrokes from the baseline. The strategy worked as Zidansek fell her first service game and then trailed 3-0. However an error-strewn game from Badosa gave her rival a break and a boost.
Zidansek started to return better and went for her shots, linking strikes with daring moves at the net to even the score at 3-3. Badosa saved a set point in the 12th game with a forehand attack but couldn't fend off the moment as her poor fall shot ended up at the internet.
Badosa trailed 4-2 in the second group after a series of unforced errors but Zidansek couldn't build on the momentum and fought with her serve, too.
The Spaniard rallied, made the decisive break in the ninth game at love and sealed the set with a big forehand.
The 23-year-old Zidansek opened this year's championship by disturbing seventh-seeded Bianca Andreescu in the first round for the first career win over a top-10 player. In that match, she had just two points from defeat at both the third and second sets.
Zidansek reached a career-high standing of No. 56 in June 2019.