Swiatek handed straight-sets defeat by Ukraine's Marta Kostyuk in the round of 16 a day after Gauff's ouster.

Iga Swiatek’s 25th birthday celebrations have turned sour at the French Open as the former champion was ousted by Ukrainian 15th seed Marta Kostyuk in straight sets in the round of 16.

Bidding for a fifth Roland Garros title, Swiatek went out 7-5, 6-1 on Sunday after a round of shock exits at this year’s tournament in the French capital.

Men’s world number one Jannik Sinner, 24-time Grand Slam winner Novak Djokovic and defending women’s champion Coco Gauff have all gone out in the past three days while Swiatek’s exit was followed by a loss for China’s number one Wang Xinyu.

It leaves world number one Aryna Sabalenka the favourite to claim her first title in Paris although Kostyuk will be one to watch as she builds the momentum that has helped her sparkle on clay this season.

“I’m still in shock,” Kostyuk said in an on-court interview.

“I feel like I’ve given myself more space to just create something, to challenge my opponents. I woke up in the morning, and all I thought was ‘What an unbelievable day I have to live today. … There’s nothing I could do other than this.’

“I try not to focus at all on winning and losing because I’m not playing tennis to win. I’m playing tennis because I love it. I want to connect to people. I want to feel this energy, … make people happy and unite people.”

There was little to separate the duo in the early exchanges as they twice traded breaks before Kostyuk came up with a tight hold in the 11th game and raised her level at the end to claim the opening set with a backhand crosscourt winner.

It was the first time that Kostyuk had taken a set off the third-seeded Pole after three straight defeats in their previous meetings, and she sensed a big upset when she went ahead 3-1 in the next set after a battling effort.

The Rouen and Madrid champion held her nerve from there to take her record on clay this season to 15-0 and book a meeting with seventh-seeded Ukrainian Elina Svitolina or 11th-seeded Swiss Belinda Bencic in the next round.

Later, Romanian ⁠⁠veteran Sorana Cirstea proved ⁠⁠that dreams have no expiration date as she beat Wang 6-3, 7-6(4) to reach her first Roland Garros quarterfinal in 17 years.

The 36-year-old, who ⁠⁠is retiring at the end of the season, advanced to the quarterfinal of a Grand Slam for just the third time in her career.

It will be her first quarterfinal in the French capital since 2009 – the longest ⁠⁠gap between the first two quarterfinals at a women’s singles major in the Open era.

“I always thought there is no expiry date for ambition and for dreams. I have so much passion for this sport,” Cirstea said after her victory.

“I absolutely love tennis, and to be able to still play at this level – have my family, my team, the ‌‌closest people watching me – it’s an absolute joy.

“I think sometimes society puts us in certain groups because of the age. But I think in life, you are free to do whatever you want, and I want to play. And here I am. Thank you, everyone, for all the support.”