American Sanya Richards-Ross won the women\'s 400m Olympic title here on Sunday in a time of 49.55sec to end a 28-year gold drought in the event for the United States. Defending champion Christine Ohuruogu of Great Britain finished second in 49.70sec while DeeDee Trotter of the United States took bronze in 49.72sec. Richards-Ross, 27, became the first American to win the Olympic title since Valerie Brisco-Hooks in Los Angeles in 1984. In a thrilling race, Richards-Ross came strongly off the bend to fight it out with Trotter while Ohuruogu finished with a stunning final burst. However, unlike in Beijing four years ago it was not enough to see the Briton - who lives near the Olympic Park - to get past the 2009 world champion. Richards-Ross, who is married to NFL defensive back Aaron Ross, shook her hands in celebration after crossing the line on realising she had gained revenge on her bitter rival for defeat for years ago.