Most sports fans don't know the names of umpires or referees, who eschew the spotlight in efforts to call a fair game. Everyone will remember Carlos Ramos.

Ramos, a Portuguese tennis umpire with several decades of experience, was accused Saturday of sexism by perhaps the greatest women's tennis player of all time.

Ramos was thrust into headlines and the target of social media vitriol thanks to a heated U.S. Open final exchange with Serena Williams, in which the tennis superstar called Ramos a thief and demanded an apology from the umpire for dishing out two penalties — one for coaching and one for smashing her racket.

After the match, the Flushing Meadows crowd was booing the 47-year-old umpire and the outcome, and Ramos was escorted off the court. Chair umpires usually are given a gift afterward during the trophy ceremony.

Williams suggested after her loss that Ramos would not have assessed a code violation on a male player for calling him a thief.

According to tennis experts and former tennis officials, Ramos is one of the few umpires who isn't afraid to call a rules violation against elite players.

Ramos also is one of the sport's few "gold badge" umpires, which is a distinction given only a handful of chair umpires based on extensive experience officiating major matches.

"Has a chair umpire ever been a bigger villain?" ESPN commentator Michael Wilbon tweeted.

While Williams acknowledged in her postgame news conference that Ramos has a strong pedigree as a chair umpire, she didn't back down on her feelings that her being penalized was an act of sexism because she said men's players have done much worse.

"I can't sit here and say I wouldn't say he's a thief because I feel like he took the game from me," Williams said. "I've seen other men call other umpires several things and I'm here fighting for women's rights and women's equality. 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 he's said thief. It blows my mind. But I'm gonna continue to fight for women."

Williams wasn't alone in suggesting Ramos' ruling was sexist.

"The hypocrisy of the umpire to penalize Serena Williams in a sport that celebrated the antics of John McEnroe...is a blatant display of sexism," actor Wendell Pierce tweeted.

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ESPN analyst Chris Evert, who won six US Open titles among her 18 Grand Slam championships, said: "The third time, to call somebody a thief, when we've heard other players, mostly men, saying four-letter words, I kind of wonder if that (impacted) the game."

Novak Djokovic went on a furious tantrum at Ramos during Wimbledon this year, and was not issued a game violation. Djokovic was upset that he received a violation for scraping his racket on the grass during his outburst, while opponent Kei Nishikori did not.

At the 2017 French Open, a furious Rafael Nadal told Ramos about the time warnings he was receiving: "Give me the warnings you can because you will not referee me any more."

And in 2016, Australian Nick Kyrgios - who is well-known for his on-court outbursts - went on an expletive-laced rant at Ramos, one of several disputes he's had with the umpire.

"I just feel like the fact that I have to go through this is an example for the next person that has emotions, wants to express themselves, want to be a strong woman," Williams said. "They're gonna be allowed to do that because of today. Maybe it didn't work out for me, but it's gonna work out for the next person."

Williams' coach, Patrick Mouratoglou, who admitted in an ESPN interview he was coaching, said that Ramos showed a double standard for singling Williams out for something "when 100% of the coaches in 100% of the matches" are doing the same thing.

The WTA issued a statement saying it would look into the dispute between Williams and Ramos.

Contributing: Josh Peter