Osaka lifted her first Grand Slam trophy last year but has failed to make it past the fourth round in Melbourne.
Naomi Osaka will take on Serena Williams at Flushing Meadows
Who is Naomi Osaka?
Osaka is a 20-year-old Japanese tennis player who was born in Osaka to a Japanese mother and Haitian father.
After moving to the USA at the age of three with her family, she currently lives in Florida.
Osaka has a dual Japanese and American citizenship but her father made the decision to register her with the Japan Tennis Association at the start of her career.
She turned pro in September 2013 at the age of 16 and qualified for her first Grand Slam in 2016 at the Australian Open.
So far some of her career her biggest wins have come against Angelique Kerber – winner of Wimbledon this year and Venus Williams who she beat in 2017 at the Hong Kong Open.
This season she also beat Maria Sharapova at Indian Wells and her US Open final opposition Serena Williams at the Miami Open.
Osaka also plays doubles with older sister Mari.
What happened in the 2018 US Open final?
Osaka won her first Grand Slam last year, but has admitted it was a "bittersweet" moment and "not the happiest memory".
The 20-year-old became the first Japanese player to win a Grand Slam when she beat Serena Williams in two sets (6-2, 6-4).
However, the final was overshadowed when Williams called referee Carlos Ramos a "thief" and later accused him of sexism.
Speaking in October she said: "Right after, the day after, I really didn't want to think about it because it wasn't necessarily the happiest memory for me.
"I just sort of wanted to move on at that point.
"Of course I'm happy that I won a Grand Slam, I don't think there's anything that can take away from that, but I feel like it was so strange, I didn't just want to think about it.
"I wanted to just push it to the side."
What is her current ranking and how high has she ranked?
Osaka started 2018 at number 68 in the WTA rankings about but an impressive season on the court has seen her dramatically rise up the rankings.
Going into Indian Wells in March, Osaka had risen to number 44 but the win saw move up to 22.
In July, she moved up to number 17 – her highest ever ranking – and going into the US Open at Flushing Meadows, she was ranked 19th.
Now going into the first Grand Slam of 2019, she is ranked 4th in the world behind Simona Halep (1), Angelique Kerber (2) and Caroline Wozniacki (3).
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