Two billionaire daughters reach the U.S. Open semifinals. Here's where their money comes from.

The two American women who have made it to the U.S. Open semifinalists not only share grit and skill, but they have something else in common: both of their dads are billionaires. 

On Thursday, 12th ranked women's tennis association (WTA) player Emma Navarro, who is from the U.S., will face off against second-ranked Aryna Sabalenka, a Belarusian, to vie for a place in the finals. On the other side of the draw, sixth-ranked Jessica Pegula, also an American, plays Karolina Muchova, who is Czech. 

Navarro and Pegula's family wealth is no secret, with Pegula previously telling Agence France Presse it's "annoying" when assumptions are made about her based on father's business success.