Williams called chair umpire Carlos Ramos a 'thief' and a 'liar' for charging her with a point penalty, before ultimately enforcing a game penalty against the American.
During and after the match, Williams pointed to sexism as part of the reason why she was given the three code violations that led to the significant penalties.
Her accusations have divided the tennis world, overshadowing Naomi Osaka's breakthrough grand slam crown.
Williams' antics during her heated exchange with Ramos has since become the biggest controversy in the sporting world for the past week, with tennis greats speaking out both to condemn and support Williams' explanations for her behaviour.
World Number 25 Barbora Strycova has now said the blow-up was motivated purely be Williams' desperate situation as she could see the match slipping away.
'This is a bulls***, for umpires being women or men doesn't matter,' Strycova told Czech website Sport.CZ.
'In comparison, I never saw (Rafael) Nadal shouting like that with an umpire.
'Ramos is tough, one of the best umpires in the world.
'He did what he had to do in that match, because she overstepped the limit.
'Did she have to behave differently only because she was Serena Williams? I find it interesting that she did it only when she was losing.
'I find it interesting that she did it only when she was losing.'
Strycova hinted that she found it strange that the WTA Tour and US Tennis Association both released statements supporting Williams.
'Me, as a woman, take a lot of warnings,' she said.
'The WTA defence surprised me. Will rules change in Serena's matches? If it's like this, let me know.'
The ITF, however, released a statement, declaring its support for Ramos.
'Carlos Ramos is one of the most experienced and respected umpires in tennis,' an ITF statement said.
'Mr. Ramos' decisions were in accordance with the relevant rules and were re-affirmed by the US Open's decision to fine Serena Williams for the three offences.
'It is understandable that this high profile and regrettable incident should provoke debate.
'At the same time, it is important to remember that Mr. Ramos undertook his duties as an official according to the relevant rule book and acted at all times with professionalism and integrity.'
She was fined $US17,000 for the blow-up. Her runner-up prize money totalled $US1.85 million.
18-time Grand Slam singles champion Martina Navratilova also hit out at Williams this week, saying the American was wrong in her outburst at the US Open women's finals.
Writing in an opinion article for the New York Times, the 61-year-old Czech-born American said a higher standard needed to be observed when Williams called chair Ramos a 'thief' and was penalised a key game in the second set.
'We cannot measure ourselves by what we think we should also be able to get away with,' Navratilova wrote.
'In fact, this is the sort of behaviour that no one should be engaging in on the court.' Williams, who was thwarted in her bid for a record-tying 24th Slam singles crown in losing to Japan's Naomi Osaka, said she was punished for saying something where men have said far worse without incurring such a penalty.
'Serena Williams has part of it right. There is a huge double standard for women when it comes to how bad behaviour is punished — and not just in tennis,' Navratilova said.
'But in her protests... she also got part of it wrong. I don't believe it's a good idea to apply a standard of, 'If men can get away with it, women should be able to, too.
'Rather, I think the question we have to ask ourselves is this: What is the right way to behave to honor our sport and to respect our opponents?'
— with AFP