The victory is Kostyuk's 12th clay-court win on the WTA Tour this season, a record surpassed only by Mirra Andreeva's 15 wins.
Kostyuk remains undefeated on clay in 2026.
"My biggest example is the Ukrainian people," Kostyuk said, noting the resilience of citizens enduring daily hardships.
"I woke up this morning and looked at all these people who woke up and kept living their lives, kept helping people who are in need," she said.
She acknowledged Ukrainian fans who came to Roland Garros to support her.
"I knew a lot of Ukrainian people would come out and support today.
My friends from Ukraine came to support and I'm very happy to have them here," Kostyuk said.
She reflected on the discipline required to compete under emotional distress.
"I'm incredibly proud of myself. I think it was one of the most difficult matches of my career," she said.
This is the third time Kostyuk has reached the second round at Roland Garros in seven appearances.
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Her next opponent will be either American Katie Volynets or French player Clara Burel.
