Serena Williams (United States)
According to espn.com, as of January 14, 2008 the second ranked woman tennis player in the world is Svetlana Kuznetsova of Russia.
At the start of the French Open Roger Federer was world number 1 for men and Serena Williams was women's number 1.
currently Roger Federer is the world's number one men's tennis player, followed by Nadal and Djokovic
Pete Sampras, a professional tennis player, was ranked as the world's number 1 tennis player in 1993. He held that position for nineteen consecutive weeks.