Naomi Osaka has withdrawn from the Western and Southern Open over the shooting of Jacob Blake and what she called the "continued genocide of black people'" by police.
The two-times Grand Slam champion announced the decision on Wednesday just after she had secured her semi-final spot in the event.
The 22-year-old released a statement on her social media, detailing her withdrawal from the tournament in a protest against ongoing racial injustice across the US.
"Before I am an athlete, I am a black woman. And 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," she posted on Twitter.
She added: "watching the continued genocide of black people at the hand of police is honestly making me sick to my stomach."
The move comes following ongoing civil unrest and demonstrations against racial injustice and police brutality across the US, compounded by the shooting of Mr Blake on Sunday in Wisconsin.
Officer Rusten Sheskey shot Mr Blake seven times in the back while holding onto his T-shirt, officials said.
On Tuesday, Mr Blake’s family and legal team held a press conference to reveal their fears that the father of three may never walk again.
A number of athletes at the National Basketball Association and Major League Baseball have staged similar protests following the shooting.
The city of Kenosha, located 40 south of Milwaukee, has faced three nights of violence and damage that followed peaceful protests.
On Wednesday it was announced that a white teenager had been arrested after two people were shot to death on the third night of the protests.
Western and Southern Open organisers have also suspended the tournaments' Thursday games in protest, and the semi-finals are now set to go ahead on Friday.
Osaka was scheduled to face Belgian Elise Mertens after defeating defeated Anett Kontaveit to reach the semi finals.
“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,” she said.
Additional reporting by Reuters
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