The backlash against Knight — and Australia more generally — intensified over 24 hours as the image made global headlines — and nowhere more fiercely than in the US.
The anger came thick and fast, and it quickly became less about Knight's cartoon and more about perceived racism in Australia.
"Trust Australia to take a debate around racialised gender dynamics and ratchet up the racism tenfold," Rachel Withers, a New York-based freelance writer, wrote in an article on The Slate. "The latest cartoon is very Mark Knight — and sadly representative of Australian cartooning and Australian racism in general."
Columnist at The Root, Michael Harriot published a scathing op-ed. He called out the cartoon for choosing to illustrate Naomi Osaka, who is Haitian-Japanese, as a "blonde, fair-skinned damn-near white woman whose complexion is the same as the umpire's."
"I don't think that Mark Knight sat down with his 64 Crayola super pack with hatred in his heart for Serena Williams. I honestly believe that, in Knight's mind's eye, that is actually how he sees Serena — as a hulking, brutish simian rampaging in front of the world," Harriot said. "Which is racist and sexist."
Meanwhile a Washington Post article said the cartoon used "dehumanising" facial features, while Brenna Edwards, a black journalist who reports on news and politics for Essence magazine in the US, told ABC News the picture "dates back to the Jim Crow era".
"Honestly, my mouth dropped open, because I do cover a lot of black news and a lot of it is hard to take, but when I saw this — a blatant caricature of one of the most celebrated athletes in the world — it was offensive, shocking and completely uncalled for," she said.
The New York Times wrote that the cartoon reflected a "wider pattern" of ignorance from Australians around race issues, saying the conversations in Australia were not as "robust and layered" as in the US.
The newspaper also tried to suggest News Corporation — owned by Rupert Murdoch, and the publisher of news.com.au — had stirred racism "for decades" and bizarrely suggested this had intensified as the Liberal party struggled in the poll.
But Knight, a veteran artist, defended his illustration — denying it was sexist or racist, saying the international storm that ensued was a "world gone crazy".
Many Australians agreed, and took to social media to express their bafflement at the extreme reaction to the cartoon.
Australian cartoonist Paul Zanetti weighed in saying it was the job of cartoonists to call out bad behaviour and not fall prey to an increasingly politically correct culture.
"Let's get some perspective. We're cartoonists. Cartoonists lampoon and caricature in equal measures. We're equal opportunity piss-takers. Whatever PR spinners do, we do the opposite," he wrote for news.com.au.
"It's been a huge response," said Today show host Georgie Gardner. "Huge reaction which I think, in itself, is fascinating. The vitriol and the hatred that has been unfurled as a result — I mean, the cartoonist, we understand, has security now outside his house. He's had death threats.
"Look, you know, the whole definition of satire is to exaggerate and to ridicule and to send up. Which is precisely what that cartoon does. It exaggerates her features in the way that — remember the cartoons we used to see of John Howard with the eyebrows, Tony Abbott's ears.
"What I'm interested to know is have we heard from Serena Williams herself as to whether she's offended by it?"
News.com.au readers agreed: "One of the greatest character traits of an Australian is the ability to laugh at themselves and not take everything too seriously," commented Martin Newell on Facebook.
Reader Stuart Bennett added: "The US public just expects everyone to knows their history and lives by their standards...ignore them they will be outraged by something else before lunch."
The Project host Waleed Aly attempted to explain why Knight was copping such backlash.
"The reason in America they're so sensitive to this, and they see it straight away and react, and that's where a lot of the reaction is coming from, is that in America those cartoons were churned out throughout the Jim Crow-era."
The term "Jim Crow" was used as an offensive term towards blacks through the end of the 19th century.
Harry Potter novelist J.K. Rowling led the charge against the cartoon yesterday, tweeting, "Well done on reducing one of the greatest sportswomen alive to racist and sexist tropes and turning a second great sportswoman (Naomi Osaka) into a faceless prop."
Comedian Kathy Griffin jumped in, as did Rapper Nicki Minaj on her Queen Radio show. And the US-based National Association of Black Journalists said the cartoon was "repugnant on many levels."
Serena Williams is yet to comment on the cartoon.
Today's front page of the Herald Sun depicts previous Knight cartoons of Australian politicians and world leaders, including former prime minister Tony Abbott depicted as Hannibal Lecter with the caption "Banned: Big ears, cannibal mask," and a topless Kim Jong-un with the words "Blocked: Belly fat, Asian stereotype."
Knight's depicting "the world's greatest tennis player spit the dummy" appears in the foreground with the caption: "Vetoed: Large hair and lips, too angry."
The tagline reads: "If the self-appointed censors of Mark Knight get their way on his Serena Williams cartoon, our new politically correct life will be very dull indeed."
