World number two and Australian Open champion Sabalenka swept 10 of the last 12 games to win 6-3, 6-2 as she kick-started her push to reach the second week in Paris for the first time.
Kostyuk honoured her pledge not to shake hands with Sabalenka in protest at Russia’s invasion of Ukraine. Belarus is a key military ally of Moscow.
“It was a very tough match, tough emotionally. I didn’t know if the booing was against me but thank you so much for your support, it’s really important,” said Sabalenka who performed a theatrical bow to the sparse Court Philippe Chatrier crowd.
Kostyuk, 20, famously refused to shake hands with Sabalenka’s Belarusian compatriot and former world number one Victoria Azarenka at the US Open last year. She opted instead for a cursory touch of racquets at the net.
The 39th-ranked Kostyuk has been a vociferous critic of the decision to allow Russian and Belarusian players to keep competing on tour since the invasion of her country.
“If she hates me, OK. I can’t do anything about that,” said 25-year-old Sabalenka on the eve of the match.
“About the no shaking, I can kind of understand them. Like I imagine if they’re going to shake hands with Russians and Belarusians, then they’re gonna get so many messages from their home countries.”
“If they feel good with no shaking hands, I’m happy with that.”
This year sees a new era at the French Open where for the first time since 2004 Rafael Nadal will not grace the famous red clay.
Injured Nadal, the 14-time champion, sits out the 2023 edition of a tournament where he has lost just three of 115 matches.
In his absence, Novak Djokovic, a two-time winner, and the man responsible for two of Nadal’s three career losses in Paris, will look to edge ahead of the Spaniard with a record-setting 23rd major.
However, he faces serious threats from the likes of Carlos Alcaraz and Daniil Medvedev, currently the world’s top two players ahead of Djokovic.
Stefanos Tsitsipas, the fifth seed and runner-up to Djokovic in the 2021 final after squandering a two-sets lead, begins his bid for a first Grand Slam later Sunday against Jiri Vesely of the Czech Republic.
Tsitsipas has enjoyed a solid clay court season, finishing runner-up to Alcaraz in Barcelona and making the semi-finals in Rome last week.
Former top 40 player Vesely has plummeted to 452 in the world and has not played a match on the main ATP Tour all year.
However, the 29-year-old Czech is not to be under-estimated — he defeated Djokovic at the 2016 Monte Carlo Masters and again in Dubai last year.
He and Marat Safin are the only players to beat Djokovic multiple times with no losses.
Andrey Rublev, the seventh seed and Monte Carlo champion in April, begins against Laslo Djere of Serbia.
Rublev has made the quarter-finals in Paris on two occasions while 57th-ranked Djere has twice made the third round.
Women’s third seed Jessica Pegula and eighth-seeded Maria Sakkari are also in action on Sunday.
Pegula, a quarter-finalist in 2022, tackles American compatriot Danielle Collins.
Sakkari made the semi-finals in 2021 where she was defeated in a three-set epic by eventual champion Barbora Krejcikova.
Another Czech player, Karolina Muchova is her opponent on Sunday.