Williams launched into a tirade of abuse directed at umpire Carlos Ramos, calling the official a "liar" and a "thief", then later accusing him of sexism, after he penalized her for on-court infractions.
Ramos is a gold-badge umpire for the ITF, who have released a statement in support of him.
On Wednesday, Strycova lambasted those accusations and offered her own suggestion for the display as she went up against the Williams camp.
Serena Williams has been lashed for her US Open final meltdown by world number 25 Barbora Strycova who rubbished the American's "sexist" claims against chair umpire Carlos Ramos.
However, the world's third-ranked men's player does not necessarily agree with the assessments of Williams and WTA chief executive Steve Simon that umpires treat women players differently from men.
"I'm fine, given the circumstances", Ramos told the Expresso, according to the Associated Press.
"He did what he had to do in that match, because she overcame the limit".
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USTA president and CEO Katrina Adams was overheard apologizing to Ramos on the sidelines of Thursday's draw ceremony.
The anonymous source believes they have not been supported by the USTA on multiple occasions, adding that Ramos was "thrown to the wolves for simply doing his job and was not willing to be abused for it".
"It's a delicate situation, but umpiring "a la carte" doesn't exist". She joins a roster of Nissan's other global ambassadors, including soccer players Gareth Bale of Real Madrid and Manchester City's record goal-scorer Sergio Aguero, who both featured prominently during Nissan's most recent UEFA Champions League sponsorship campaign.
Strycova also questioned the Women's Tennis Association's and the United States Tennis Association's decision to leap to Williams' defence.
Ramos was unable to defend himself over the weekend as the rules prevent umpires from commenting on the matches they oversee. "Don't you worry about me!"
Williams was seeking to equal Margaret Court's record of 24 Grand Slam singles titles and was facing 20-year-old Osaka at Flushing Meadows in her first major final.
Ramos will return to the chair on Friday, officiating the men's semi-final of the Davis Cup, he confirmed. "They feel that no one has their back when they have to make unpopular calls".