The No. 3-seeded Halep made an unlikely comeback in her quarterfinal match against No. 5 Elina Svitolina, trailing a set and two breaks, with her opponent serving for the match, but coming from the brink to win 3-6, 7-6 (6), 6-0.
"I was around watching [Martina] Hingis come up and [Steffi] Graf come up and [Monica] Seles come up, and I just see something special in this young lady and the fact that she's so fearless", Evert said of Ostapenko.
She sealed her place in the final with a forehand winner - her 50th winner of the encounter - and minutes later "Happy Birthday" was being sung in French, led by interviewer and former Wimbledon winner Marion Bartoli.
"I hope this time I can play better", Halep said, "and I can win it". I was just trying to stay aggressive and to go for a shot when I could.
She allowed her opponent just four winners in the first set and was four games to the good in the second before the Romanian's remarkable turnaround.More news: TODAY'S FORECAST: Showers and thunderstorms, high near 81
Czech second seed Pliskova would have become world number one next week had she won the second semi-final.
She dug incredibly deep and managed to force a tie break winning five out of the last six games, even surviving a match point.
Halep, the 2014 runner-up, was down 5-1 in the second set, then was a point from losing while down 6-5 in the tiebreaker but came up with a backhand victor down the line to extend the match.
"I think probably I will have a lot of attention when I come back home".
"I let her back into the game a little bit", admitted Svitolina, who will rise to a career-high of fifth next week despite the defeat.
Serbian Ivanovic was honored in a ceremony on Philippe Chatrier court after Thursday's match: The 2008 champion retired in December.More news: 79 people feared dead in London high-rise fire
"It will be exciting playing in a Grand Slam semifinal on my birthday".
"It's truly special. As an athlete, when you start playing tennis, you want to win a Grand Slam".
The Latvian, who turned 20 on Thursday, is also the youngest woman to advance to the final of a major since a 19-year-old Caroline Wozniacki finished runner-up at the 2009 US Open.
Today at the French Open is all about the ladies, as two top-seeds clash in one match and two surprise contestants battle it out in another for a spot in the finals.
Yet to win a WTA Tour final, Ostapenko could be the first player to lift the French Open as her maiden title since Gustavo Kuerten in 1997.
Despite the big match ahead, she said she would still take time to celebrate her birthday. "That's it. It's over", Halep said afterwards.More news: Taylor Swift returns to streaming sites
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