Serena Jameka Williams is an American professional tennis player. She has been ranked singles world No. 1 by the Women's Tennis Association for 319 weeks, including a joint-record 186 consecutive weeks, and finished as the year-end No. 1 five times. She has won 23 Grand Slam singles titles, the most by any player in the Open Era, and the second-most of all time. Along with her older sister Venus, Serena Williams was coached by her parents Oracene Price and Richard Williams. Turning professional in 1995, she won her first major singles title at the 1999 US Open. From the 2002 French Open to the 2003 Australian Open, she was dominant, winning all four major singles titles to achieve a non-calendar year Grand Slam and the career Grand Slam, known as the "Serena Slam". The next few years saw her claim two more singles majors, but suffer from injury and decline in form.