She has also won the year-ending Sony Ericsson Championships twice and the singles gold medal at the 2004 Summer Olympics in Athens. Tennis experts cite her mental toughness, the completeness and variety of her game, her footspeed and footwork, and her one-handed backhand as the principal reasons for her success. When Henin retired for the first time in 2008, Billie Jean King said that “pound for pound, Henin is the best tennis player of her generation” and “Justine is the best women’s athlete I’ve ever seen.” January 26,2011, Henin announced her definitive retirement from professional tennis.