21-year-old Sofia Kenin of U.S. holds her Australian Open trophy in Melbourne, Australia, February 2, 2020. /CFP

22-year-old Naomi Osaka of Japan wins the U.S. Open women's singles title in New York, U.S., September 13, 2020. /CFP

At age 20, Naomi Osaka in action on her route to winning the 2019 U.S. Open in New York, September 8, 2019. /CFP

At age 23, Ashleigh Barty of Australia wins the French Open women's singles title in Paris, France, June 9, 2019. /CFP

At age 28, Simona Halep of Romania wins the Wimbledon Championships in London, UK, July 14, 2019. /CFP

At age 27, Simona Halep in action on her way to win the French Open women's singles title in Paris, France, June 9, 2018. /CFP

Bianca Andreescu (L) of Canada and Serena Williams exchange stand on the stage for the trophy ceremony. At age 19, Andreescu won the 2019 U.S. Open singles title after defeating then 38-year-old Williams in straight sets in New York, September 7, 2019. /CFP