Williams had asked for an apology after being given a warning by chair umpire Carlos Ramos. He said Williams received coaching during her Grand Slam match. She took issue with the allegations and called Ramos a thief during an argument.
Williams then smashed her racket later in the match after she had a bad game, ESPN reported.
Osaka went on to beat Williams 6-2, 6-4 for her first Grand Slam title.
Here are five facts about Naomi Osaka:
Her parents: Leonard Francois, her father, is Haitian. Tamaki Osaka, her mother, is Japanese. The couple met when Francois was a college student studying in New York who was visiting Hokkaido. Tamaki Osaka's father said she had brought disgrace to her family when she was dating a foreign person who was black. They moved to Osaka, where Naomi Osaka was born, The Washington Post reported.
>> Read more trending news
She shares her name with her hometown: Naomi Osaka has said she grew up in New York, then moved to Florida when she was either 8 or 9 years old. But her last name, Osaka, is the same as the city of her birth, Osaka, Japan. She has joked that everyone who is born in the city shares the last name, The Washington Post reported. Despite having a home in Florida, she plays for Japan, The New Yorker reported.
Turned pro: Naomi Osaka turned pro at the age of 15 in 2013. She had a first-round win in 2014 against 2011 U.S. Open Champion Samantha Stosur, according to Bleacher Report. She has also beaten big tennis stars like Maria Sharapova and Venus Williams, according to Bleacher Report.
"Newcomer of the Year:" Many who are not regular watchers of tennis may not recognize Naomi Osaka, but she's been around, winning the "Newcomer of the Year" title at the Women's Tennis Association Awards in 2016. That same year she was also named WTA "Breakthrough of the Month" after entering the Australian Open and reaching the third round of the French Open and US Open. That year she ended the season ranked 48th.
First Japanese player to win Grand Slam title: With her defeat of Serena Williams, Osaka is now ranked seventh in the world for singles women, according to the WTA. She has a singles record of 25-10 and two WTA singles titles under her belt. So far this year, she has made more than $5.7 million in prize money, taking home more than $7 million over her career. In March 2018, she was the first Japanese woman to win the Indian Wells Masters in California. It was her first WTA title, according to the New York Times. In that tournament, she was unseeded, the Times reported.