Serena Williams is calling out sexism in tennis. Here's why.

Serena Williams' heated dispute with the umpire during the US Open final is the latest controversy involving the tennis superstar in recent months.

Japan's Naomi Osaka beat Williams on Saturday in a Grand Slam showdown that ended in tears for both players -- for different reasons. What was supposed to be a fairy-tale matchup for Osaka and the player she idolizes, spun out of control after Williams was handed code violations that she described as unfair.

The 23-time Grand Slam champion has faced racist attacks for most of her career, and after the match Saturday, she said she believes sexism is rampant in the sport.

Here's a look back at some recent times sexism has been called out on the tennis court:

Serena calls the umpire a 'thief'

Williams accused umpire Carlos Ramos of sexism after she was handed a series of code violations during Saturday's match.

Ramos first gave Williams a code violation warning for coaching after he ruled that her coach, Patrick Mouratoglou, gave her hand signals from the stands.

Then she got a point penalty for smashing her racket, followed by a game penalty for verbal abuse after she confronted the umpire.

"You stole a point from me and you are a thief," Williams told Ramos prompting the game penalty ruling.

At a news conference following her loss, Williams said she's seen male players call other umpires "several things."

"I'm here fighting for women's rights and for women's equality and for all kinds of stuff. For me to say 'thief' and for him to take a game, it made me feel like it was a sexist remark," she said.

"He's never taken a game from a man because they said 'thief.' For me it blows my mind. But I'm going to continue to fight for women," Williams said.

Billie Jean King, a tennis legend and equal rights advocate, agreed with her.

"When a woman is emotional, she's "hysterical" and she's penalized for it. When a man does the same, he's "outspoken" & and there are no repercussions. Thank you, Serena Williams, for calling out this double standard. More voices are needed to do the same," King tweeted.

For Christine Brennan, a CNN sports analyst, the clashes between Williams and the umpire show that women are not being treated equally in the tennis world.

"We know that there's quite a history to it. Think of John McEnroe, think of Ilie Nastase, Jimmy Connors, Andre Agassi. These men all berated chair umpires, famously so. Commercials have been made. McEnroe has done, 'you can't be serious' and all the other tirades, top of his lungs over the years and none of them received a game penalty," Brennan said.

"Would he (umpire) have done that with a man? History has said, no. He would not have done that with a man."

Retired US tennis star Andy Roddick tweeted, "I've regrettably said worse and I've never gotten a game penalty."

Alize Cornet is penalized for fixing her top

Williams isn't the only tennis player to find herself at the center of a gender-focused controversy.

French tennis player Alize Cornet received a code violation a few weeks ago for briefly taking off her shirt on the court.

During a 10-minute break from the blistering heat at Flushing Meadows, Cornet rushed off-court to change her shirt. When she returned, she realized that she was wearing it the wrong way and fixed her top.

In a statement, the US Open said it regretted the way Cornet was treated. The organization added that all players are allowed to change their shirts while sitting in their chairs while female players have the option to change shirts in "a more private location close to the court, when available."

However, male players have changed shirts many times on court without a problem.

On Tuesday, John Isner changed his shirt 11 times throughout his three-plus hour match against Juan Martin del Potro. A day later, Wimbledon champion Novak Djokovic sat shirtless for several minutes while his opponent, John Millman of Australia, stepped away to change his shirt during a quarterfinals match. Neither of them was penalized.

And Rafael Nadal regularly takes off his shirt after winning a match.

Officials introduce dress code after Serena's catsuit

In Williams' first major tennis match after giving birth, her outfit stole the show.

In May, Williams wore a black catsuit at the French Open that helped her blood circulation after a difficult childbirth last September. Her Nike outfit, which she said was inspired by the movie "Black Panther," was praised by her fans but had tennis officials shaking their heads.

French Tennis Federation President Bernard Giudicelli announced late last month that he will be introducing a new dress code that would ban players from wearing such form-fitting clothes at the tennis tournament.

"One must respect the game and the place," Giudicelli said.

Unlike Wimbledon, which has an all-white dress code, the French tournament never had a dress code before.

Williams, who has dealt with body shaming and even criticism over her dark features, took the high road and said she was not upset.

"We already talked. We have a great relationship," Williams said of Giudicelli last month, laughing as she added, "Everything is fine, guys."

After the controversy, she left the suit at home and wore a stylish black-and-brown one-shoulder silhouette dress with a tulle skirt at her first US Open match this year. The $500 dress was designed by Louis Vuitton menswear artistic director Virgil Abloh in partnership with Nike.

While Serena took the dress code change in stride, many of her fans -- including some famous ones -- called the move sexist.

Actress Elizabeth Banks wrote on Twitter: "The amount of control men feel the need to exert over women is petty-level with this one. Serena Williams is the GOAT. The game respects HER."

Television show creater Shonda Rhimes wrote: "The game seems quite content to be played no matter what women wear. Perhaps this man should focus on his own fashion choices and respect the GOAT's right to wear whatever the hell she pleases. #getoffhercourt"

By Nicole Chavez, CNN.The-CNN-Wire™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.

The Gayly. 9/9/2018 @ 10:16 a.m. CST.