Keys slipped two breaks down in the second but although she pulled one back Stephens served out for the match.
It was just her fifth loss in 25 Grand Slam quarter-finals. "I'm happy with that", the 24-year-old said. It also was a rematch of the U.S. Open final won by Stephens last September. It's just how it's happened for me", Stephens said, "I think once I get going in a tournament, I'm pretty consistent, which is good. "I think I've developed a lot as a tennis player". But it's a little weird.
Halep won in an hour and 32 minutes, and was awaiting the victor of the second all-American match between Madison Keys and Sloane Stephens. He was also able to raise his level when in danger, saving three break points in the eighth game of the third set with great shot-making, and four more in the final set.
It will be Halep's second consecutive Grand Slam final after she lost the title match at the Australian Open in January.
In the first all-American Roland Garros semi-final since 2002, the 10th-seeded Stephens stayed composed throughout as Keys, who has not won a set against her in three meetings, peppered the court with unforced errors. I'm playing well, in a good space. I just went and searched for her in the training room.
Halep assured herself of retaining the No. 1 ranking and reached her third final in Paris.
However, her sights now turn to the final where she is desperate to erase the memories of last year's horror show where she surrendered a set and a 3-0 lead to lose to Jelena Ostapenko.
Two-time major victor Kerber raced into a 4-0 lead in the first set before having to rely on a tiebreak to nudge her ahead.
Sharapova looked nervous from the beginning and was never allowed to settle as Muguruza posted her first victory against the Russian at the fourth attempt.
Muguruza's opponent Lesia Tsurenko lasted just two games before retiring hurt.
"It was very nice to play like that", Halep said.
Sharapova might prefer to be described as a veteran rather than an antique, but the analytics that matter to her have nothing to do with birthday candles at this point. And it's always tough against her.
"But to have had the victories that I have had, to have the results that I have, obviously moving a step in the right direction". But she failed to convert any of those, and Halep held there, before breaking at love to end it.
Muguruza hasn't dropped a set and has spent a combined total of 90 minutes on court in her last two matches (one shortened by her fourth-round opponent, who quit due to injury after only two games) - less time than Halep and Germany's Angelique Kerber logged in their first two sets Wednesday.
"Before, I gave it a lot of importance so that's why you're fighting every week, and I got there".
LeBron James went off the backboard to himself in Game 3
The rest of the 7 roster spots will have to be filled out mostly through minimum contracts they negotiate with players. Like Durant, Curry has not forgotten that loss. "It's nearly like playing the Patriots ", James said after the game.