France's world No 361 Lois Boisson shocked US third seed Jessica Pegula in a thrilling three-set battle on Monday to keep her childhood "dream" of winning the French Open alive.

The 22-year-old wildcard won 3-6, 6-4, 6-4 in a gripping fourth-round match lasting two hours and 40 minutes and next meets Russian sixth seed Mirra Andreeva for a place in the semifinals.

Boisson becomes the first French singles player to reach the last eight of their home Grand Slam since 2017, and first as a wildcard since Mary Pierce in 2002.

"I would not have believed if you told me two weeks ago," said Boisson, who is the only French player left in the tournament.

"But I trust in myself. I knew I could do it even if I knew she was very strong. It was a beautiful performance.

"Obviously, it's a dream to begin with. First, to play at Roland Garros. Then, to win it, that's a goal too."

Boisson is the lowest-ranked woman to reach a Grand Slam quarterfinal since former top-20 player Kaia Kanepi at the 2017 US Open.

She is also the first player to make the women's quarterfinals on their Grand Slam debut since Carla Suarez Navarro at Roland Garros in 2008.

Boisson had been set to make her French Open bow last year, but tore the anterior cruciate ligament in her left knee the week before the tournament.

The 31-year-old Pegula, the 2024 US Open runner-up, could not stop the momentum as Boisson dug deep on her favored red clay surface, buoyed by the cheering home fans on Court Philippe Chatrier.

Boisson conceded the first set in just over half an hour with four double faults.

But playing her first Grand Slam main draw and only her second tour-level event, the Frenchwoman came back with a vengeance in the second set on a surface she says "suits (her) style of play".

"I feel best and super happy on clay," she told journalists.

"It's the surface I've played most on."

She began to mix up her game with well-timed drop shots — 34 in total — and lobs — of which she had 32 — firing down winners, with a powerful two-handed backhand breaking Pegula's serve to lead 5-4.

Boisson converted two of her six break-point chances, cupping her ear to hear the roar of the crowd as she held serve to love to set up a third-set decider.

"It was incredible when the points were very tight at the end," she said of the support.

"The last two games were very tense because there was a lot of pressure."

The final set produced some epic games, especially the last two as Boisson showed no sign of the pain in her troublesome left knee that had hampered her in the previous round.

Whenever Boisson dragged out the rallies, the American finally cracked with an unforced error.

The player from Dijon, France held off four break points as she served for the match at 5-4 in the third set before sealing a stunning victory thanks to a powerful forehand winner.

"The match point, I admit I was pretty tense because I only had one," she said.

"I was really hoping to make it on that one. When I saw that my forehand was winning, everything was released. All the pressure, all the stress at the end of the match."

For Pegula, it was a game she let slip.

"I felt like the match turned into exactly how she wanted to play, and that's unfortunate for me," said the American.

"I had a million chances and it just didn't go my way in those kinds of big moments."

Boisson next plays 18-year-old Andreeva who won 6-3, 7-5 against Russian-born Australian Daria Kasatkina.

"It's not the same style of play, she varies more (than Pegula)," said the Frenchwoman.

"There are a few points I need to adapt but I won't change anything."

AFP