Varvara Gracheva produces comeback for the ages to stun Kristina Mladenovic

20-year-old Varvara Gracheva produced one of the most stunning comebacks in Grand Slam history on Wednesday as she came back from 6-1, 5-1 down to beat 30th seed Kristina Mladenovic.

For the vast majority of the encounter it looked as if the experienced Mladenovic would enjoy a comfortable win over her novice opponent.

Yet Gracheva, playing in her first Grand Slam, somehow dug into the depth of her inner strength and started to fight back. At 5-1 down she broke back but Mladenovic put her under pressure immediately, earning the chance of four match points.

But Gracheva wouldn’t give in, she held and forced a tie break, where she dominated her clearly rattled opponent. At this stage Mladenovic had fallen to pieces and incredibly Gracheva proceeded to bagel her to win the third.

Mladenovic was one of several athletes placed under an "enhanced protocol plan" for being in contact with compatriot Benoit Paire, who tested positive for the novel coronavirus and was withdrawn ahead of the Grand Slam.

Speaking after the game, Mladenovic was furious with the organisation of the tournament and didn't hide her emotions.

The United States Tennis Association's (USTA) protocols have meant that players in contact with Paire are being tested for Covid-19 every day rather than once in four days and are confined to hotel rooms.

Mladenovic, who along with partner Timea Babos are the top seeds for women's doubles, earlier said she felt like being stuck inside a "bubble within a bubble".

She was lost for words to explain her loss after having four match points on Gracheva's serve at 5-2 in the second set.

"At 5-2, I just collapsed. I have nothing more to say, I'm completely devastated," she said. "It's absolutely abominable how they are treating us, but I don't want that to be an excuse for my defeat.

"It's not the USTA's fault that I didn't convert four match points, don't get me wrong."

Mladenovic said despite "thirty negative tests" she was still treated like a prisoner and a criminal.

"The conditions are atrocious and if I had known that playing cards for 40 minutes with a player who tested positive, but ultimately negative, would have resulted in these consequences, I would never have set foot in this tournament," she said.

Next up for the talented youngster is Croatia’s Petra Martic.