Tennis officials are making Serena Williams pay—literally—for standing up for herself on Saturday against a U.S. Open umpire.

The U.S. Tennis Association has handed the tennis great a $17,000 fine for her pointed conversation with umpire Carlos Ramos in which she politely informed him that she does not have to cheat to win and called him a “thief” for taking a point from her, the Washington Post and other news organizations are reporting.

Williams’ conversation with the official, which included a drop-the-mic moment as she finished what she had to say and strutted away, came amid an accusation that her coach, Patrick Mouratoglou, was giving her hand signals from the sidelines.

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The incident came as Williams lost to Naomi Osaka, a player of Haitian descent from Japan, prompting many on social media to note that Osaka’s win did not mark a loss for Williams, but rather a victory for all Black women tennis players. Williams has been outspoken about her view that officials administer drug tests to her more often than other players, and recently was taken to task by the French Open, which banned catsuits after she wore one on the court.

Williams has not responded directly to the umpire incident, but did post an image on Instagram on Sunday of a girl in school clothes with a large yellow “S” on her black shoulder bag. “What does your ‘S’ stand for?” Williams posted, adding the hashtag, “#BeSeenBeHeard.”

At least one historic figure in the world of tennis said on Twitter that she has Williams’ back, calling out what she views as sexism;

“Several things went very wrong during the U.S. Open women’s finals today,” posted retired tennis star Billie Jean King. “Coaching on every point should be allowed in tennis. It isn’t and, as a result, a player was penalized for the action of her coach. This should not happen.”

She received widespread support on social media from fans and celebrities alike:

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