Svitolina was serving for the match at 5-1 in the second set but choked and lost 12 of the 13 remaining games as Halep reached the semis for the second time since 2014, the year she finished runner-up, with a 3-6 7-6 (6) 6-0 win. It wasn't because I lost, but because of my attitude and him feeling like I gave up.
Garcia, victor of a fiery duel with compatriot Alize Cornet in the previous round, seemed to wilt in the second set, unable to match her Czech opponent.
Halep will meet second seed Pliskova for a place in Saturday's final after the second defeated Garcia 7-6 (7/3), 6-4. "That's maybe why I won this match".
"I think I was strong mentally". She was playing hard and strong. Down 5-6 in the tie-break, she sent a sizzling backhand victor to stave off the match-point, levelling proceedings and as Svitolina crumbled, Halep took home the set to level the match at one-set all. He said yes, because I improved a lot, and he saw that I really wanted to change that.
After falling an early break down to Pliskova, Garcia recovered well to restore parity and then survived a further three break points to force the tie-break.
The 25-year-old then broke the Frenchwoman as she served to stay in the match to clinch just her second appearance in the last four at a Grand Slam.
The semifinals are set at Roland Garros, and while one is a birthday bash between Timea Bacsinszky and Jelena Ostapenko, another could determine something greater as No.2 seed Karolina Pliskova finds herself one win away from becoming World No.1. "Before the tournament I wasn't sure if I could play good tennis on clay".