The 2014 finalist would have been the heavy favorite had she not sustained an ankle injury in the final of the Italian Open last month against Elina Svitolina -- a week after defending her crown at the Madrid Open. However, the third seed has brushed aside any fitness concerns by reaching the last eight without conceding a set.
On Monday she crushed Carla Suarez Navarro -- the 21st-seeded Spaniard who had beaten Halep in their four previous clay duels -- 6-1 6-1 on a blustery day in Paris to set up a rematch with Svitolina, who rallied from 5-2 down in the third set to end the run of Croatian qualifier Petra Martic 4-6 6-3 7-5.
After Venus Williams and Svetlana Kuznetsova lost Sunday, the French Open -- which is missing Serena Williams, Maria Sharapova and Victoria Azarenka -- is guaranteed of producing a first-time grand slam winner.
Halep hopes it will be her.
Her great form, she said, can be attributed to a more positive attitude on court since early April.
"I work hard and I changed," Halep told reporters, Monday. "I changed pretty fast."
Halep revealed that her highly respected coach and television analyst Darren Cahill -- formerly in the corners of Andre Agassi and Lleyton Hewitt -- stopped traveling with her following a tough loss to Johanna Konta in the quarterfinals of the Miami Open in March.
"He was upset after Miami's match," Halep admitted.
Indeed Cahill wasn't pleased with Halep's downcast demeanor between the second and third sets in Miami.
During an on-court coaching visit, Halep called herself "bad" and "(ridiculously) bad" after she failed to serve out the match in the second set and blew a 5-4 lead in the second-set tiebreak.
The Australian replied: "You've been in this position many, many times before and most times you come out second best. So right now you have an opportunity to change things. It's up to you.
"You can decide what you want to do here. You can go down this path and that's fine. Or you can take a deep breath, put the towel over your head and try to get a little better in this situation.
"It's up to you and comes from within."
Following the defeat, Halep reflected and then beat Konta weeks later in the Fed Cup in Romania prior to making the semifinals in Stuttgart.
'I felt ashamed'
"He was home, I was home," Halep said. "He just told me that we will talk after Paris. And then he liked how I was in Fed Cup. And then in Stuttgart. So I think when I finished Stuttgart, he said he saw enough and he's ready to come back.
"I asked him if he wants to come back before Madrid. He said yes, because I improved a lot, and he saw that I really wanted to change that.
"So the desire that I had in that moment made him come back and just be ready for me.
"So I'm okay. Now I'm happy that I can be positive on court, and I will never be negative like I was in Miami, because I didn't like when I saw the video, I felt ashamed about what I did. So hopefully it is not going to happen again."
Halep also wants to avoid a repeat of the result in the Rome finale, when Svitolina -- seeded fifth in Paris -- won the biggest title of her career.
The Ukrainian said she suffered a back injury -- which also arose in Rome -- before taking to the court against Martic.
But almost out of the tournament at 2-5 in the deciding set, she got into "Svitolina mode."
"I heard that after 2-5 I missed only four points, so probably this is Svitolina mode," said Svitolina, who like Halep is renown for her court coverage. "I just try to find myself into this zone where I don't do much unforced errors and still play aggressive."
Karolina Pliskova and Caroline Garcia square off in the other bottom-half quarterfinal after advancing in contrasting fashion. Pliskova -- the second seed competing on her least productive surface -- needed three sets to beat 97th-ranked Veronica Cepede Royg 2-6 6-3 6-4, with No. 28 seed Garcia comfortably getting past fellow Frenchwoman Alize Cornet 6-2 6-4.
The latter contest was billed as a grudge match after Garcia and Cornet said they were not on good terms, stemming from the former pulling out of a Fed Cup series in April.
However when the encounter ended Monday, they exchanged a warm handshake and kisses on the cheek.
Murray: 'Terrible tragedy'
Losing a set in the first round, nearly taken to five sets in the second and playing two sets that could have gone either way against Juan Martin del Potro on Saturday -- he won them both -- men's No. 1 Andy Murray got some respite, Monday.
He eased past Russia's Karen Khachanov 6-3 6-4 6-4 to make the quarterfinals, where his opponent will be eighth seed Kei Nishikori. Despite suffering a bagel -- or 6-0 set -- for the second straight day, the Japanese baseliner rallied to beat Fernando Verdasco 0-6 6-4 6-4 6-0.
Although Murray leads their head-to-head 8-2, Nishikori toppled the Scot when they last met at a major at the 2016 US Open.
When that match was brought up in his press conference, Nishikori incredibly claimed he forget who won.
Murray's first thoughts post-match Monday weren't about tennis but instead Saturday's terrorist attack
in London, where he resides, and the terrorist attack in Manchester about a week earlier.
"Obviously it's a terrible tragedy in London," Murray, who recorded his 650th career win, told the crowd. "We've had also in Manchester six or seven days ago. Paris also in the last few years.
"I'm sure everyone would join me in sharing our thoughts and prayers with everyone who's been affected by this.
"It's something that's affected large parts of Europe and all around the world."
"I'm grateful you're all still coming out to support the tennis and that I get the chance to play in front of you."
Although an all-French women's final remains a possibility, the last French man in the draw, Gael Monfils, was knocked out to extend Les Bleus men's drought for another year -- Yannick Noah was the last winner in 1983. Monfils lost to 2015 champion Stan Wawrinka 7-5 7-6 (9-7) 6-2.
The Swiss confronts Croatia's Marin Cilic in the last eight after the 2014 US Open winner advanced when South Africa's Kevin Anderson retired while trailing 6-3 3-0.