Naomi Osaka is reportedly set to sign Adidas' biggest deal with a female athlete — and it could make her one of the highest-paid women in sports

Naomi Osaka is reportedly set to sign the biggest deal Adidas has ever agreed to with a female athlete.

Osaka, a 20-year-old tennis player, just won the US Open — her first Grand Slam title. She defeated the 23-time major winner Serena Williams in straight sets, 6-2, 6-4, on Saturday at Arthur Ashe Stadium in New York, collecting a $3.8 million paycheck.

But her new deal with Adidas could dwarf her earnings from tennis, The Times reports.

Osaka is reportedly on a "six figure" salary with Adidas that will expire this year.

The Times says a contract worth an estimated $8.5 million a year will be announced Thursday. This would be Adidas' biggest deal with a female athlete, according to Yahoo, which also says it would see the Japanese star rocket up Forbes' list of the highest-paid women in sports.

With the new endorsement deal, Osaka could become the second-highest-paid woman this year, above her fellow tennis player Caroline Wozniacki but one rung below Williams.

Osaka has been thrust into the global spotlight because of the nature of her victory over Williams, who received three code violations during the US Open final match. The first violation was for coaching, which Williams argued against. "I don't cheat to win — I'd rather lose," she said. Her coach later acknowledged giving hand signals, though it was unclear whether Williams saw them. She was later given a violation for smashing her racket, costing her a point. Her third violation, for calling the umpire Carlos Ramos a "thief," cost her a game.

Williams has since been lampooned by an Australian newspaper cartoonist, bringing even more notoriety to the match.

The massive Adidas renewal could be a reflection of Osaka's increased standing in the sport and around the world, Yahoo reports.

The Adidas deal could be a sign of things to come for Osaka, as the New York Post believes another endorsement, potentially with a car manufacturer, could also be on the horizon. The publication says Osaka is likely to become "a branding sensation."