Maria Sharapova's superior earnings potential over Serena Williams may not be such a mystery, just like Williams' dominance of Sharapova on the tennis court may not be such a mystery.

In an article depicting Sharapova's rise in becoming the world's wealthiest female athlete, Bloomberg didn't reveal any secrets or extraordinary theories as to why the Russian - generally considered the No. 2 player in the world (she's actually No. 4 right now) - out-earns No. 1 Williams by 2-to-1 away from the court.

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Or why Williams has a 17-2 record and won 16 straight against Sharapova.

"The lopsided run is partly a result of a series of major shoulder injuries Sharapova had in the mid-2000s that weakened her once spectacular serve," Bloomberg reported. "This left her without the weapon she needed to gain an early edge in matches, to maintain momentum in the middle, and to rescue her when she was down."

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As for Sharapova's dominance, Bloomberg adds that after her Wimbledon breakthrough, she was ideal as a celebrity endorser for the rich pockets of the tennis community - blonde, 6-foot-2 and beautiful and a more competitive version of fellow Russian tennis player/model Anna Kournikova.

Sharapova recently signed on with Porsche, and a marketing representative explained the attraction.

"She looks like a model at an auto show, but Viktoria Wohlrapp, a senior marketing manager for Porsche, says that's not why they hired her," Bloomberg reports. "Porsche is the most profitable auto brand in the world, but 85 percent of its customers are men. The company has been plotting how to sell more cars to women for years, and management says it hopes that having a prominent female athlete associated with the brand might help correct the gender imbalance. So it signed Sharapova to a three-year deal.

"...Can Sharapova actually sell cars? 'That's very hard to say,' Wohlrapp admits. "But for us, it's an image thing. It was very important to find someone who matches the brand, and we feel like Maria and Porsche is a good thing."

Asked about Sharapova as an endorsement figure, Harvard Business School professor Anita Elberse said, "These companies wouldn't be doing it if they didn't see some value."

So while Williams is chasing history with 20 Grand Slam titles and getting halfway to winning all four slams in a single season, Sharapova and her five slams continue to be the big winner off the court.