From Ms Magazine:

Rivals In women’s professional tennis today, the spiciest and most thrilling rivalry is between two women who don’t even want to compete against each other — sisters Serena and Venus Williams.

In the 1970s and ’80s, though, the two greatest female competitors weren’t stymied by blood relation. They went at it, unconstrained, over the course of 16 years and an unfathomable 80 matches, with first one then the other proving unbeatable, yet neither backing down. Along the way, they formed their own surprising bond, which transcended a lack of almost any similarity beyond their unswerving drive to win.

Chris Evert: cool, metronomic, girlish; a baseline player from a devout Catholic family in suburban Florida . Martina Navratilova: overemotional, unpredictable, jockish; a serve-and-volleyer from Communist-run Czechoslovakia . Chris, the girl next door; Martina, the defector from a seemingly alien world. Chris, straight; Martina, gay.

Yet they hit it off from their first meeting at a tennis tournament as teenagers. When they weren’t running each other ragged on the court, they could joke and laugh and put The Game aside. Only when Navratilova came under the sway of early-1980s girlfriend Nancy Lieberman — who felt rivals should barely be civil to each other — did the friendship waver, but they reconnected once Lieberman left the scene.

More here.