Many tennis stars experience success off the court. They rake in millions in endorsements. Some lend their names to tennis academies and jewelry. Others pitch products and write best-selling books.
But that's not enough to make this list.
John McEnroe, Cliff Drysdale and Mary Carillo all have successful sportscasting careers. But moving into a broadcast booth after retirement is a natural transition for athletes. So you won't find them on this list.
This list is for players who were bona fide stars on the court. They developed a passion for something beyond tennis and succeeded.
Bjorn Borg runs a company that makes high-end underwear. It's sold all over the world. Venus Williams' interior design firm V Starr has upscale hotels as clients.
That's why Borg and Williams make the list for tennis stars with the most impressive second careers.