Tennis: Naomi Osaka's incredible earnings for the last year

2020 was a year to forget for a large majority of the world population but it proved to be pretty lucrative 12 months for tennis star Naomi Osaka.

The Japanese 23-year-old earned a record US$55.2m (NZ$75.8m) according to Sportico's ranking of the world's 100 highest-paid athletes.

A staggering US$50m of that come from off the court endorsements according to reports.

The four-time major winner has partnered with two dozen brands including Tag Heuer, Nissan, Levi's, Louis Vuitton, BodyArmor, Shiseido, airline All Nippon Airways and a reported eight-figure deal with Nike.

She also is an investor in a restaurant chain Sweetgreen and a co-owner of the North Carolina Courage in the National Women's Soccer League.

Unlike NFL star Colin Kaepernick, Osaka's willingness to speak up about social issues has improved her brand. Osaka sent shockwaves throughout the tennis world by withdrawing from her WTA Western & Southern Open semifinal in New York last August to protest the police shooting of an unarmed black man in America, and the entire sport soon followed suit.

The move came in the wake of African-American Jacob Blake being shot in Kenosha, Wisconsin, and the NBA's Milwaukee Bucks boycotting a scheduled playoff game.

"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," Osaka posted in a statement on Twitter at the time.

"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."

The WTA, ATP and USTA released a joint statement shortly after saying play would be paused for a day.

Osaka then continued her fight racial injustice at the US Open when she brought seven face masks to New York, each bearing the name of a victim of racism or police brutality. She went onto win the event for the third of her four grand slam titles.

Osaka, the current world number two, has earned US$19.7m since her first WTA match in 2013.