For many tennis fans, the story of Serena Williams begins in 2001 at the Indian Wells Masters tournament. 

While 19-year-old Serena was on the court, facing off against Kim Clijsters, her sister Venus and father Richard Williams entered the stadium — to boos.

Venus had pulled out of a match against Serena earlier, due to tendinitis, but a rumor floating around held that Richard had forced her to withdraw, in order to orchestrate a win for Serena. 

"I've never seen anything like it," remarked one of the TV commentators. 

In a rebuke to the crowd, Richard raised his fist: the Black Power salute. He later said he heard people shouting the N-word, and issuing physical threats. Serena was the local girl, having been raised in nearby Compton, but the crowd overwhelmingly backed the Belgian Clijsters.

Indian Wells has been haunted by the controversy ever since — as has the sport. After all, tennis is supposed to be civilized, the sport of kings. It's also defined by its overwhelming whiteness — among both players and fans. 

If Serena Williams wins the US Open this weekend, she will have bagged her 22nd major title and completed the first Grand Slam since Steffi Graf achieved the feat in 1988. But her cultural significance extends far beyond that, especially to the African American fans who have followed her career.

Imani Perry, a scholar of African American studies at Princeton, recalls that as a 7-year-old, she was the only black child among 300 attending a tennis camp in Evanston, Ill.

"Other campers wouldn't speak to me or sit with me," said Perry. 

When she took the court, her opponents simply sat down on the other side of the net and refused to play. This was in 1980. She never picked up a racket after that.

But she has always loved watching the Williams sisters on TV. She turns off the sound, though, "because there's so much animosity," she said. Commentators complained about how "noisy" the Williams' sisters' hair was, or "that their father wasn't equipped to coach them. There was so much constant criticism."

She said that black women in particular feel that "it's this unbelievable resilience that they've displayed."

Kavitha Davidson, a sports columnist at Bloomberg View, said Serena contends regularly with racism and sexism, or 'misogynoir' as coined by scholar Moya Bailey. That explains why there is a long list of tweets comparing Serena to a gorilla, and why she earns $10 million less in annual endorsements than Maria Sharapova, despite a far better record. For her most ardent fans, those who think she's the best player ever, this is an inexcusable double standard. 

But is she the best ever? For some long-time observers, that's an open question. 

Los Angeles Times sports columnist Bill Dwyre said it's hard to definitively rank Williams above previous greats like Steffi Graf, Martina Navratilova or Margaret Court, all of whom have held the 'best ever' title at various points.

"The eras are different. The time is different, the equipment is different, the balls fly faster, the crowds are different, the marketing and branding that they do is much different," said Dwyre. 

But her success stands out. And it's because of the timing. 

"So much is frankly devastating and depressing at this moment about race in this country," said Professor Perry. "She allows people just to feel pride and joy in a way that's unfiltered and unmediated."