Naomi Osaka has withdrawn from Western & Southern Open in protest against racial injustice hours after booking her place in the semi-finals.
The 22-year-old joins similar protests by players in the National Basketball Association and Major League Baseball following the police shooting of Jacob Blake on Sunday in Wisconsin.
It is unclear if Osaka will reconsider her decision after organisers suspended play for Thursday as a mark of protest. The semi-finals will now be played on Friday, which is scheduled to be the final day of the event.
"Before I am a athlete, I am a Black woman," she said on Twitter.
"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."
Osaka defeated Anett Kontaveit 4-6 6-2 7-5 to reach the semis where she was scheduled to face Belgian Elise Mertens, who needed just over an hour to defeat qualifier Jessica Pegula 6-1 6-3 and reach her first Premier 5 semi-final.
By pulling out of the semi-finals Osaka is giving up the chance to sharpen her game further ahead of the US Open Grand Slam but she said it was important for tennis to address the issue of racial injustice.
"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," said Osaka.
British number one Johanna Konta also marched into the last four with a 6-4 6-3 win over Greece's Maria Sakkari, who entered the match fresh off a win over Serena Williams for one of the biggest wins of her career.
A tight first set ultimately came down to one break of serve, which Konta converted in the third game. Konta broke two more times in the second, including in the final game where she secured the win after a Sakkari double fault.
Up next for Konta, who is reaching top form ahead of the second Slam of the year, is a clash with former world number one Victoria Azarenka, a 7-6 6-2 winner over Ons Jabeur of Tunisia.
The tournament, the final tune-up before the US Open, is being played at Flushing Meadows in New York this year instead of Cincinnati due to the Covid-19 pandemic.
