NEW YORK • Naomi Osaka has been to the top of the world, fallen into the depths of depression, and now the Japanese tennis star is back to the summit again.

The 22-year-old has become the world's highest-paid female athlete, making US$37.4 million (S$53.3 million) in the past 12 months for an earnings record, Forbes magazine reported on Friday.

She is also the first Asian athlete to have achieved this feat. The twice Grand Slam winner edged out US rival Serena Williams by US$1.4 million in prize money and endorsement income over the past year.

Both shattered the old single-year earnings mark of US$29.7 million set in 2015 by Russia's Maria Sharapova, who retired in February with five Grand Slam titles.

"To those outside the tennis world, Osaka is a relatively fresh face with a great backstory," University of Southern California sports business professor David Carter told Forbes.

"Combine that with being youthful and bicultural - two attributes that help her resonate with younger, global audiences - and the result is the emergence of a global sports marketing icon."

Osaka, whose father was born in Haiti and whose mother is Japanese, ranks 29th on the 2020 Forbes list of the world's 100 top-paid athletes, four spots ahead of 23-time Grand Slam champion Williams.

The complete list, due to be released this week, has not featured two women since 2016.

Since Forbes began tracking women athletes' income in 1990, tennis players have topped the annual list of female top income earners every year.

But Williams, Sharapova, China's Li Na and now Osaka are the only women to rank among the 100 top earners in sports since 2012.

Williams, 38, had been the world's highest-paid female athlete in each of the past four years. Sharapova, 33, ruled for the five years before that. The pair had each earned over US$300 million, much of it in endorsement deals.​

Osaka's rise to the top of the list was a perfect convergence of her heritage and her success on court.

She won back-to-back Grand Slam titles at the 2018 US Open and 2019 Australian Open, her victory over Williams in the Flushing Meadows final the first Slam singles crown for a Japanese woman.

Now ranked 10th, she also became Asia's first world No. 1 last year after her Melbourne win.

But, following her remarkable triumphs, Osaka fell into a slump and admitted that she was suffering from depression. Not only did she split with her coach Sascha Bajin, who had been a large part of her rise, but she also found it tough to handle her new-found fame and said that it was a struggle to deal with the media glare.

"The kid was depressed out there," Osaka said in April last year in Stuttgart, where she bounced back to reach the semi-finals but withdrew because of injury.

"Definitely, I've put a lot of pressure on myself and found it hard to deal with in the first few tournaments (after her two Slams)."

Throughout her ups and downs, she was supported by many and became a popular endorsement figure in Japan, ahead of the now-postponed Tokyo Olympics and remains a sponsor's dream ahead of next year's rescheduled Games.

Nike signed an apparel deal with Osaka last year that paid her US$10 million in the past year and runs till 2025.

Part of the stable of management group IMG, she currently has 15 sponsorship deals, including with global brands such as Nike, Nissan Motors, Shiseido and Yonex.

Osaka told Forbes last year: "I tasked my team with finding brands that align with my personality and my interests."

She has the liberty to choose now that she is at the top and it is likely that she will only get richer, as brands line up to associate themselves with one of the brightest stars of tennis' new generation.

AGENCE FRANCE-PRESSE, REUTERS