|Venue: Flushing Meadows, New York Dates: 31 Aug-13 Sept|
|Coverage: Selected live radio and text commentaries on BBC Radio 5 Live Sports Extra, BBC Sounds, the BBC Sport website and app.|
She was playing at her first Grand Slam and trailing 6-1 5-1 to a seed – but then Varvava Gracheva managed the impossible.
The Russian 20-year-old saved four match points as she climbed spectacularly out of a hole to beat Kristina Mladenovic 1-6 7-6 (7-2) 6-0 in the US Open second round.
“It is definitely the most painful match and loss I have had in my career,” France’s Mladenovic said.
“I just collapsed.”
Gracheva will face eighth seed Petra Martic next after the Croat beat Ukraine’s Katerina Bondarenko 6-3 6-4.
Meanwhile, sixth seed Petra Kvitova overcame an early setback to advance.
The two-time Grand Slam champion came back from a break down in the first set and saved a set point to beat Ukrainian Kateryna Kozlova 7-6 (7-3) 6-2.
But Kvitova’s compatriot Marketa Vondrousova, the 12th seed, became the highest-ranked woman to make an exit.
The 2019 French Open runner-up lost 6-1 6-2 to Belarus’ Aliaksandra Sasnovich.
Former champion Angelique Kerber came through a tough encounter with fellow German Anna-Lena Friedsam, winning 6-3 7-6 (8-6), while there were also victories for Croatian eighth seed Petra Martic and Estonian 14th seed Anett Kontaveit.
Top seed Karolina Pliskova is in action later on Wednesday when she faces a tricky test against former world number four Caroline Garcia of France, while Japanese fourth seed and 2018 champion Naomi Osaka takes on Italy’s Camila Giorgi.