A true American hero, Martina Navratilova, turned 50 years old today. Born on Oct. 18, 1956 in Czechoslovakia, she defected to the United States after losing in the semifinals of the U.S. Open in 1975. She became an American citizen in 1981 and at the U.S. Open final that year, she was given one of the most memorable standing ovations in tournament history. Not only was the crowd cheering her valiant effort in a heartbreaking 1-6,7-6-7-6 loss to Tracy Austin, they were cheering a fellow American. Martina went on to win four US singles titles during the 1980s over the likes of Chris Evert and Steffi Graf and played in her last singles final at the Open in 1991 when, after losing to Monica Seles, she told the crowd: "I'm so damned proud to be an American." Then last month, Martina took the mixed doubles title at the age of 49 in her last match as a professional.