Halep went from out-of-sorts to on-target against Kerber, scrambling to every ball and staying the course to erase an early deficit.
The world No. 3 took that setback on the chin and prowled around the court with a spring in her step as she broke again for a fourth time to lead 2-1.
"It was very nice, this headline, and I know that some people think I will never make it, but I'm sure I'm going to make it", the seventh-seeded Garcia told reporters. I think everything will be normal.
This was when the Halep could have gone into a shell, but as she has so often shown in both wins and losses, she will fight it out till the decider, keep running till someone is out of gas.
"When you're writing an autobiography, I don't think there is any reason to write anything that's not true", said Sharapova after being knocked out of Roland Garros by Garbine Muguruza 6-2, 6-1 in the quarter-finals.
Sharapova, back at the claycourt slam for the first time since 2015 following a doping-ban, walked on court with two French Open crowns to Muguruza's one and a 3-0 head-to-head record against the reigning Wimbledon champion. The victor earns a berth in the final at Roland Garros, plus the number one ranking that now belongs to Halep.
"I think she's right now probably the best player".
The Romanian is chasing a first Grand Slam title having lost the final of this event a year ago to Jelena Ostapenko.
But she has not dropped a set in this year's tournament and dominated Sharapova with booming groundstrokes and superb returning that earned six breaks.
"I just have to go find her, because I need to tell her some juicy stuff", Stephens said, declining to reveal the topic. Muguruza has won seven of her last nine matches on clay court.
Nadal lost the opener 6-4 against 11th-seeded Diego Schwartzman but began to play better after a rain delay of just under an hour.
Halep, 28, will play 2016 champion Garbine Muguruza, of Spain, in the semi-finals on Thursday. She is capable of moving Muguruza and forcing her out of her comfort zone in a way Sharapova could not.
The two former Paris champions had not been inconvenienced by too much tennis over the past few days - Serena Williams pulled out of her match with Sharapova while Muguruza's opponent Lesia Tsurenko lasted just two games before retiring hurt.
The No. 3-seeded Muguruza had lost all three previous meetings against Sharapova, who won two of her five Grand Slam titles at Roland Garros. If she can channel that same degree of aplomb and expertise in the semi, Halep doesn't have much of a chance.
Follow along for a breakdown of quarterfinal action at the second Grand Slam of the year.
It is the first time that two American women have reached the last four at Roland Garros since 2002, when Serena Williams beat sister Venus in the final, after a semi-final win over Jennifer Capriati.
It wasn't an easy win till Kerber needed a medical timeout in the third set.
"I don't think you have to be mean in order to win matches".