Paris - Simona Halep admitted on Monday she was "ashamed" that her on-court behaviour prompted respected coach Darren Cahill to call a temporary halt to their partnership.
Australian Cahill quit in frustration at the Romanian's negative demeanour after she surrendered winning positions to Britain's Johanna Konta in Miami in March.
Cahill called it quits until the duo were reunited just in time for the build-up to the French Open where the 26-year-old reached the quarter-finals on Monday.
During the changeover before the final set in Miami, Cahill spent the best part of three minutes sitting next to Halep, desperately trying to coax her out of her negativity.
"You can give up on yourself, but I'm not," said Cahill.
It didn't work as Halep slipped to a dispiriting defeat.
"I didn't like it when I saw the video (of the Cahill pep talk), I felt ashamed about what I did," said Halep.
"But now I'm happy that I can be positive on court, and I will never be negative like I was in Miami."
Halep said she had reached out to the 51-year-old Cahill who has worked with likes of Andre Agassi, Andy Murray and Ana Ivanovic in his time.
"He told me we will talk after Paris. But then he liked how I was in Fed Cup and then in Stuttgart," she explained.
"So I think when I finished Stuttgart, he said he had seen 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.
"Now I'm happy that I can be positive."
Halep, the third seed, made the quarter-finals at Roland Garros on Monday for the first time since 2014 when she went on to finish runner-up to Maria Sharapova.
She needed just an hour to coast to a 6-1, 6-1 win over Spain's Carla Suarez Navarro.
It was her first win over Suarez Navarro on clay in six attempts.
"I played my best match of the tournament. I served well and opened up the court," said Halep, who will become the new world number one if she wins the title on Saturday.
The 25-year-old Halep will tackle Ukraine's fifth seed Elina Svitolina for a semi-final place.
The two met in the Rome final on the eve of Roland Garros when Halep suffered an ankle injury which threatened her appearance in Paris.
Svitolina ended the dream run of world number 290 Petra Martic with a 4-6, 6-3, 7-5 win.
But Martic, who came through qualifying, threw away a golden chance to make the quarter-finals after leading 5-2 in the final set.