Serena Williams has been handed a heavy fine for her US Open final outburst as the 23-time grand slam singles winner hit out at “sexism” in tennis.

Williams imploded in an ill-tempered US Open women’s singles final on Sunday (AEST), calling chair umpire Carlos Ramos a “thief” and a “liar” in an ugly match in which she was handed three separate code violations and eventually a one-game penalty.

The United States Tennis Association (USTA) announced on Monday they had fined Williams $US17,000 ($23,920) for the code violations –$US10,000 for the “verbal abuse” of Ramos, $US4,000 for being warned for coaching and $US3,000 for smashing her racquet.

Naomi Osaka, the 20-year-old Japanese player who stunned Williams 6-2 6-4 in the Flushing Meadows decider, was booed by the pro-American crowd during the post-match presentation, reducing her to tears.

Japan’s first grand slam winner idolised Williams growing up and was eventually given some respect after her opponent called for the booing to stop, but the reception – and the American’s mid-match antics – significantly overshadowed the result.

https://twitter.com/OffsidersABC/status/1038598727852687360

Williams said she would not change her behaviour in a post-match press conference in which she criticised double standards in tennis and rejected suggestions she was being coached during the match – something her coach, Patrick Mouratoglou, later confirmed he was trying to do.

“I can’t sit here and say I wouldn’t say [Ramos is] a thief, because I thought he took a game from me,” Williams said.

“But I’ve seen other men call other umpires several things. And 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. I mean, like, he’s never taken a game from a man because they said ‘thief’. For me, it blows my mind.”

Williams’ third code violation saw her hit with a one-game penalty, taking the second set score from 4-3 to 5-3 in Osaka’s favour.

Williams referred to an incident earlier in the tournament in which Frenchwoman Alize Cornet was penalised for changing her shirt on court as an example of how men and women were treated differently.

“I’m going to continue to fight for women and to fight for us to have equal – like Cornet should be able to take off her shirt without getting a fine. Like, this is outrageous.”

Osaka could not contain her emotions after being booed. Photo: Getty

Williams then stood up and left her press conference to applause from reporters.

She also said Osaka “deserved to win” and that she would “always stay gracious and to stay humble”.

Mouratoglou admitted to ESPN he was trying to coach Williams but that “all coaches are coaching throughout the match”.

Calls for penalties for Serena, but lots of support too

Olympian and prominent sports commentator David Culbert said Williams deserved a lengthy suspension from tennis for her behaviour.

“What a disgrace Serena Williams. Playing every card under the sun to excuse her appalling behaviour,” he posted on Twitter.

“Naomi Osaka deserves her moment in the sun and Williams stole it.

“If tennis has any integrity and respect for their officials Serena Williams should receive a long suspension from the game. Serial offender in abusing and bullying officials.”

Highly respected Fairfax journalist Caroline Wilson said Williams was “doing a terrible disservice to women’s rights, to the #metoo movement, to gender equality”.

“What she is is a bad sport … she’s not fighting for women’s rights. That is a joke,” Wilson said on ABC’s Offsiders.

Williams destroyed her racquet. Photo: Getty

Williams also received lots of support, with former world No.1 Billie Jean King particularly strong on the issue.

“Several things went very wrong during the US Open women’s finals today. Coaching on every point should be allowed in tennis,” she said.

“It isn’t, and as a result, a player was penalised for the actions of her coach. This should not happen.

“When a woman is emotional, she’s “hysterical” and she’s penalised 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.”

Former American star Andy Roddick said on Twitter it was the “worst refereeing I’ve ever seen” while television personality Ellen DeGeneres added that Williams had “changed the world for the better” and “that’s worth more than a match to me”.

The USTA released a statement praising Williams’ behaviour during the post-match ceremony.

USTA president Katrina Adams, who said that Williams was an “inspiration to me”, said: “What Serena did on the podium today showed a great deal of class and sportsmanship.

“This was Naomi’s moment and Serena wanted her to be able to enjoy it. That was a class move from a true champion.

“I know that she was frustrated about the way the match played out, but the way she stepped up after the final and gave full credit to Naomi for a match well played speaks volumes about who she is.”

What did you think of Serena’s behaviour? Let us know in the comments below