World number one Simona Halep fought back from a set down to beat Angelique Kerber 6-7 (2-7) 6-3 6-2 and move into the French Open semi-finals.
Two-time finalist Halep remained on course for her first Roland Garros title by beating the German 12th seed.
Halep, 28, will play 2016 champion Garbine Muguruza, of Spain, in the semi-finals on Thursday.
Muguruza moved into the final four with a convincing 6-2 6-1 victory over Russia's Maria Sharapova on Wednesday.
Sloane Stephens faces Madison Keys in a repeat of the 2017 US Open final in an all-American line-up in the other semi-final.