Iga Swiatek's 25th birthday celebrations turned sour at the French Open on Sunday as the former champion lost 7-5 6-1 to Ukrainian 15th seed Marta Kostyuk, her ‌bid ⁠for a ⁠fifth title ending just when she had looked to be rediscovering her rhythm.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.Read More: Norway Chess: Gukesh downs Praggnanandhaa to revive title hopes; Divya storms into leadIt 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 of Roland Garros.