Serena WilliamsSerena Jameka Williams (born September 26, 1981) is an American professional tennis player who is a former World No. 1 and currently ranked World No. 4 in singles and No. 5 in doubles with sister Venus Williams. The Women's Tennis Association has ranked her World No. 1 in singles on five separate occasions. She is considered to be one of the greatest women's tennis players of all-time in a career hampered by numerous injuries. She regained this ranking for the fifth time on November 2, 2009. She became the World No. 1 for the first time on July 8, 2002.