Mladenovic, the number 30 seed was playing the world 102, Varvara Gracheva, a 20-year old Russian playing in her first Grand Slam.
And everything appeared to going to plan, as she quickly took the first set 6 1, and then raced into a 5 -1 lead. And, even after the Russian took the following game, Mladenovic had four match points in the next Gracheva service game.
However, she squandered them all and subsequently imploded. She was to one just one more game in the entire match, as the young Russian levelled on a second set tie-break, and then romped through the third to love.
Gracheva will now play Jennifer Brady of the United States.
Afterwards, whilst Mladenovic was not offering any excuses for her meltdown, she did offer her comments on the treatment she and some of her compatriots had suffered at the hands of tournament organisers in the past few days.
It follows the positive test for Covid-19 returned by Benoit Paire at the weekend. He is now in quarantine, whilst compatriots like Richard Gasquet, Adrian Mannarino, and Gregoire Barrere were required to go to a bubble within a bubble. That means they have been required to stay in their rooms, and have been tested for coronavirus every day, as opposed to once every four days.
Mladenovic feels like she has been treated like a criminal just because she played cards with Benoit for 40 minutes last week, and that, had she known she would be locked-up like a prisoner, she would never have entered the tournament.
Unfortunately for her, she cannot leave yet. She is still entered in the womens doubles where she is the number one seed, together with Timea Babos of Hungary.