However, Venus' career continues to decline while Serena's remains remarkable.
This year, a documentary called "Venus and Serena" was released. It's about their storybook rise from the tennis courts of Compton to Grand Slam champions.
But when sports historians write the final chapters on these two great players, will Venus be one volume in a series of books written about Serena?
Has Serena totally eclipsed Venus?
A few years ago, it would have been unthinkable to suggest that Venus, less than two years older than Serena, would be considered out of her sister's league in terms of talent and accomplishments.
But that's where we are.
Venus, winner of seven Grand Slams, dropped to No. 35 in the WTA rankings. She has earned only $203,095 in prize money this year. She earned $30,147 of that playing doubles with Serena in the Australian Open.
Serena also has nearly 3 million more Twitter followers than Venus.
Their father, Richard Williams, predicted that Serena would be better than Venus. But did he believe she would be this much better?
Serena has 16 Grand Slam singles titles, more than double that of Venus' total. Serena also has nearly double the career prize money.
Of course, Venus has been slowed by Sjogren's Syndrome. In 2011, shortly after being diagnosed with the illness, Venus told the Daily Mail that, "I won't let it beat me."
But with Father Time and Sjoren's playing doubles against her, Venus may simply be outmatched.
Still, despite her recent struggles, Venus trails only Serena among active players in prize money and Grand Slams won.
A few months ago, they met in the semifinals of the Family Circle Cup in Charleston, S.C. The match was unimpressive. Serena blew past Venus, 6-1, 6-2, just like she does most opponents.
Venus lost in the first round of the French Open and had to withdraw from doubles.
Even the most hopeful of Venus' fans must realize she is unlikely to experience a late-career, Serena-like surge.
Venus will always be part of "The Williams Sisters," one of the greatest sports stories of all time.
Serena, however, has turned a page. She is writing her own story.
Once a tag-a-long, Serena has emerged from the shadow of her big sister.
She stands alone.
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