'What is happening': Tennis world in disbelief over French Open chaos

The French Open will have a surprise women's finalist after the draw continued to be blown completely wide open on Sunday.

Seventh seed Serena Williams was the biggest casualty of the day, with Victoria Azarenka (15th) and Marketa Vondrusova (20th) also crashing out in the fourth round.

'WHAT A DISGRACE': Outrage over Roger Federer withdrawal

'STAGGERING': Ugly Naomi Osaka twist in Federer controversy

Williams had looked solid through her first three matches and had surged into title contention with a number of big names falling by the wayside.

However she was defeated in straight sets by 21-year-old Elena Rybakina as her quest for a record-equalling 24th major continues.

Williams went into the match against Rybakina as the only top-20 player left in the bottom half, but an unexpected finalist is now guaranteed after the 39-year-old lost 6-3 7-5.

Rybakina will play doubles partner Anastasia Pavlyuchenkova in the last eight, who followed up her victory over third seed Aryna Sabalenka by knocking out Azarenka 5-7 6-3 6-2.

It will be Pavlyuchenkova's first quarter-final match in Paris since a run to the same stage a decade ago when she was 19.

The other quarter-final in the bottom half will pit Spain's Paula Badosa against Tamara Zidansek.

Zidansek, who beat Sorana Cirstea 7-6 (4) 6-1, is the first player representing Slovenia to reach the last eight at a slam.

Badosa's run is not as surprising given her excellent form on clay, defeating former French Open finalist and 20th seed Vondrousova 6-4 3-6 6-2.

The shock losses for Williams, Azarenka and Vondrusova mean Sofia Kenin (4), Iga Swiatek (8) and Maria Sakkari (17) are the only top-20 players remaining in the women's draw, with Kenin set to play Sakkari on Monday.

The extraordinary drama left the tennis world stunned.

Victoria Azarenka blasts French Open officials

After her loss, Azarenka criticised the French Open for scheduling men's matches in nearly all night slots this year, saying the tournament lacks real gender equality.

The twice grand slam champion also said practice courts were not prepared properly and complained that organisers of the clay-court major were unhelpful.

The night session, in place for the first time, is being played in an empty stadium because of the 9pm local curfew due to the COVID-19 pandemic.

"What concerns me is when somebody from the French federation is continuously trying to say that there's equality and only pointing to prize money, which is true," Azarenka told a press conference.

"Everything else, I wouldn't even agree a little with that. And that's disappointing.

"I think there are enough examples over the years where we've heard remarks towards women, where we've seen two women's semi-final matches playing on the outside courts.

"I think sometimes you need to hold some people accountable for some of those things and not continuously point to the obvious of prize money."

Asked how she would have reacted if asked to play in a night session here, she said: "I will answer that whenever I will be asked if I would like to play a night session or not. Honestly, that would be already a step forward."

with AAP

Watch 'Mind Games', the new series from Yahoo Sport Australia exploring the often brutal mental toil elite athletes go through in pursuit of greatness:

Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.