• The pair did not have the traditional pre-match photo following the coin toss.
• After Sabalenka sealed the victory, Kostyuk walked straight to shake the umpire's hand and then to her chair, prompting boos from the crowd on Court Philippe-Chatrier.
Ukraine's Marta Kostyuk was booed off the court for avoiding a handshake with Aryna Sabalenka after the Belarusian's first-round win at the French Open.
Second seed Sabalenka delivered a dominant performance to win 6-3 6-2.
Belarus is an ally of Russia and allowed troops to use its territory to launch last year's invasion of Ukraine.
"I thought the boos were against me so I felt a bit surprised," said Australian Open champion Sabalenka. "But then I felt your support."
The pair did not have the traditional pre-match photo following the coin toss. After Sabalenka sealed the victory, Kostyuk walked straight to shake the umpire's hand and then to her chair, prompting boos from the crowd on Court Philippe-Chatrier.
Sabalenka was startled by the initial booing, thinking it was directed at her, before realising it was aimed at world number 28 Kostyuk when the crowd again booed as the Ukrainian left the court.
"It was a very tough match, tough emotionally," said Sabalenka in her on-court interview.
Prior to the match, Sabalenka - who has previously said "no one supports war" - had said she understood if Kostyuk "hates" her.
Kostyuk, 20, refused to shake hands with Belarus' Victoria Azarenka at last year's US Open.
Sabalenka is one of the favourites for the title at Roland Garros and could become world number one during the fortnight if Iga Swiatek fails to reach the quarter-finals.
After a shaky start from Sabalenka, featuring two double faults, Kostyuk got the first break but it appeared to shock the 25-year-old into finding another level.
She broke back immediately to start a devastating run of six successive games to which Kostyuk had no answer.
Though she pulled a game back, Sabalenka continued to command play, saving two break points in what proved to be her final service game as she wrapped up the win on her first match point.
She will face either Hungary's Panna Udvardy or fellow Belarusian Iryna Shymanovich, a qualifier, in the second round.