French teenager Diane Parry came from a set down to shock the defending champion Barbora Krejcikova 1-6, 6-2, 6-3 on centre court in front of a delighted partisan crowd.
The match, played under the roof due to the rain lashing down on the French capital, started ominously for the former junior world number one.
The world number 96 lost the first four games in 17 minutes.
But she rallied and at least got herself on the board before Krejcikova wrapped up the opener in 30 minutes.
After Parry lost the first two games of the second set, the match turned as Krejcikova's level dropped.
Unforced errors on her forehand started to mount up allowing Parry to get back on equal terms.
From there the local heroine won the next four games to level the match.
Krejcikova broke at the start of the decider and in a see-saw game fended off three break points and threw in three double faults on her way to holding for a 2-0 lead.
Even though she boasted the advantage, the tone of the match had changed.
The first two games of the decider had taken 19 minutes.
And the 26-year-old Czech could not consolidate. Parry broke to level at 2-2 and held for a 3-2 lead.
With the fans sensing an upset, her every winning point was raucouosly cheered.
She broke again to lead 5-3. And though she lost the first two points as she served for the match, a second ace started a roll which ended with her arms aloft, a famous victory and centre court adulation
"I've always dreamed of playing on this court," Parry said. "I'd like to thank the fans for their support. They helped me to go for it."
World number one Iga Swiatek, who had been seeded to meet Krejcikova in the final, encountered no such resistance.
She swept into the second round with a straight sets demolition of Lesia Tsurenko from Ukraine.
It finished 6-2, 6-0 and was all over in 54 minutes on a centre court.
Swiatek, who won the title in 2020, moved to the top of the world rankings following the retirement in March of Ashleigh Barty.
She has ruled the roost since then witth titles on the hard courts in Miami and on the clay courts in Stuttgart and Rome;
"I know that at some point the streak will be stopped," said the 20-year-old after her 29th consecutive victory.
"I just want to be concentrating on the tennis and not thinking about the numbers."
Former world number one Naomi Osaka was another high profile casualty in the women's draw. She went down to the 27th seed Amanda Anisimova 7-5, 6-4.