Naomi Osaka Is Ready to Win Virtual Mario Tennis Tournament: I'm 'Keeping My Competitive Spirit'

Naomi Osaka is getting back on the tennis court today — sort of.

The tennis champion is one of many stars participating in Sunday's Stay at Home Slam, a virtual tennis tournament during which they'll play the Mario Tennis Aces game for Nintendo Switch to raise money for COVID-19 relief.

Competitors will play the video game from their homes, and each will receive $25,000 donated to the charity of their choice, with the winner of the tournament receiving an additional $1 million donation.

Osaka joins other superstar tennis champions, including Serena and Venus Williams, as well as Maria Sharapova.

"I mean what's not to like?" Osaka tells PEOPLE of deciding to sign on. "First and foremost: we are giving well over $1 million to COVID-19 related charities, the real reason we all signed on. It's really amazing for us all to be able to come together in such a short time frame to help."

Osaka is personally playing for Hope for Haiti, a non-profit organization focused on helping the Haitian people in a variety of areas. Donating to the organization "means a lot," she says.

"I'm also a big gamer, so this is right in my wheelhouse," she admits, "even if Mario Aces is a bit more about luck than a traditional game I am still keeping my competitive spirit."

Osaka is paired with Hailey Bieber for the fun competition, which she says she's "so excited" about.

"I heard she has been practicing with Justin, so I'm hoping we do well," notes Osaka of her fellow bareMinerals ambassador.

The 22-year-old is grateful to be in a position where she's able to do something charitable during these uncertain times of pandemic.

"It's always important to give back, one of the best parts about being in the spotlight is your ability to reach people around the world and inspire or help in some way," she says. "Playing for Hope for Haiti and knowing that I am helping provide people and kids with lasting impact as it pertains to health, the economy and general wellbeing of those affected by COVID-19 — that is really special and personal to me."

It's, of course, also been a weird time for the sport of tennis, as many professional tournaments have been canceled or are under threat of being canceled.

"Like everyone, I am taking the time to be thankful for the things I have, taking the time I may not always have when on the road to read, cook, draw, listen to music and remotely connect with friends and family," Osaka explains. "It's a time where you do what you can because, in the end, we are all here and in this together."

While at home, Osaka has also been "trying to keep my body and mind in shape," as she cannot be on the courts. She's been stretching, doing strength and conditioning workouts, and running. She's also keeping in touch with her trainer and conditioning coach.

And when pro tennis returns, Osaka says she'll be ready: "There is no question about that."

The Stay at Home Slam will be streamed exclusively on Facebook via Facebook Gaming at fb.gg/FacebookGaming and IMG's tennis Facebook page at 4 p.m. EST Sunday.