Sabalenka shrugs off jeers to make French Open second round
World number two Sabalenka came through 6-3, 6-2 in a match for which the build-up had been overshadowed by the continuing sporting fallout from Russia's invasion of Ukraine.
Sabalenka had said on the eve of their clash that she understood if Kostyuk felt "hate" towards a player from Belarus, a military ally of Russia.
However, the 25-year-old Sabalenka was unfazed on Court Philippe Chatrier, winning 10 of the last 12 games to reach the second round.
At the conclusion of the match, Kostyuk walked quickly to her chair, ignoring her opponent before Sabalenka performed a theatrical bow to the sparse crowd as jeers echoed around the stadium.
"It was a very tough match emotionally. I thought you guys were against me but I then really felt your support," said the Australian Open champion who has the chance to take Iga Swiatek's world number one spot at Roland Garros.
Kostyuk, 20, has been outspoken about the tennis world's response to the Russian invasion of her homeland, saying anti-war platitudes weren't enough.
When she won her first career WTA title in Austin earlier this year with victory over Russia's Varvara Gracheva, she dedicated it to her country and "all the people who are fighting and dying".
On Sunday, Kostyuk, ranked 39, enjoyed the first break of the match to lead 3-2 but the more powerful Sabalenka roared back, sweeping the next four games to claim the opener.
Australian Open champion Sabalenka, who has never got past the third round in Paris, broke in the opening game of the second set and backed it up with a hold for 2-0.
There was no way back for Kostyuk as Sabalenka set up a second round clash with either compatriot Iryna Shymanovich or Panna Udvardy of Hungary.