Three-time Grand Slam tennis champion Naomi Osaka of Japan has invested in the North Carolina Courage of the National Women's Soccer League (NWSL) to become a team owner, the U.S. top-flight club said Thursday.

"The women who have invested in me growing up made me who I am today, I don't know where I would be without them," Osaka, the world No. 3, wrote on Twitter.

"Throughout my career I've always received so much love from my fellow female athletes, so that's why I am proud to share that I am now an owner of the NC Courage."

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Osaka, 23, was named Forbes' highest-paid female athlete in May last year when she surpassed her idol Serena Williams, raking in $37.4 million in prize money and endorsements over 12 months.

The Courage won back-to-back titles in 2018 and 2019 after moving to North Carolina.

Stephen Malik, chairman and founder of the club in 2017, said: "I am thrilled to welcome Naomi as an owner of the North Carolina Courage.

"She brings an invaluable viewpoint on topics beyond sports. I cannot think of anyone better to help us as we continue to make a difference in our community and inspire the next generation of women."

Osaka, who won the US Open last year, has used her standing in the sport to fight for racial justice. At every round of the tournament in New York, she wore masks bearing the names of Black Americans who died as a result of racial injustice and police brutality.