Tokyo: Naomi Osaka pulled out of the semifinals of the Western & Southern Open tennis tournament on Wednesday in protest at racial injustice.
Osaka, who has a Japanese mother and Haitian father and has been a vocal supporter of the "Black Lives Matter" movement, said in a social media post: "Before I am an athlete, I am a Black woman".
Her decision follows protests over the police shooting of Jacob Blake, a Black man, in the city of Kenosha, Wisconsin, on Sunday.
Earlier on Wednesday, the National Basketball Association postponed three play-off games after the Milwaukee Bucks boycotted Game 5 of their play-off series against Orlando Magic in protest over racial injustice.
In Osaka's statement, posted on Twitter, she said she was making the decision to move the conversation forward.
"As a Black woman I feel as though there are much more important matters at hand that need immediate attention, rather than watching me play tennis," the world No. 10 wrote.
"I don't expect anything drastic to happen with me not playing, but if I can get a conversation started in a majority white sport I consider that a step in the right direction.
"Watching the continued genocide of Black people at the hand of the police is honestly making me sick to my stomach."
Osaka beat Anett Kontaveit 4-6, 6-2, 7-5 on Wednesday to reach the semifinals, where the two-time Grand Slam champion was due to face Elise Mertens.
Thursday's matches suspended
Meanwhile, the matches will be suspended on Thursday in protest against racial injustice, organisers said in a statement.
"As a sport, tennis is collectively taking a stance against racial inequality and social injustice that once again has been thrust to the forefront in the United States," organisers said in a statement.
The tournament was scheduled to hold semifinals in both the men's and women's draws on Thursday but they will now resume on Friday.