Serena Jameka Williams (born September 26, 1981) is an American professional tennis player. She was ranked as the world No. 1 in women's singles by the Women's Tennis Association (WTA) for 319 weeks (third-most of all time), and finished as the year-end No. 1 five times. Williams won 73 WTA Tour–level singles titles, including 23 major women's singles titles—the most in the Open Era, and the second-most of all time. She is the only player to accomplish a Career Golden Slam in both singles and doubles, and the only player to have simultaneously held Olympic gold and all four major titles in both singles and doubles. Along with her elder 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 consecutively (each time over Venus in the final) to achieve a non-calendar year Grand Slam (nicknamed the "Serena Slam"). After injuries, Williams returned to dominance in 2012, claiming Olympic gold (completing the career Golden Slam in singles) and winning eight out of thirteen singles majors, including all four in a row in 2014–2015 to achieve a second "Serena Slam". At the 2017 Australian Open, she won her 23rd major singles title, surpassing Steffi Graf's Open Era record. Williams also won 23 WTA Tour-level doubles titles, including 14 major women's doubles championships, all with her sister Venus. The pair was undefeated in major doubles finals, earning the best unbeaten record in major finals in any discipline of the sport. The sisters achieved a non-calendar year Grand Slam between the 2009 Wimbledon Championships and the 2010 French Open. Williams won four Olympic gold medals, three in women's doubles—an all-time joint record in tennis, shared with her sister. The duo are the only women in the Open Era to win Olympic gold in both singles and doubles. Williams also won two mixed doubles majors, both in 1998. She is the only player, male or female, to complete three career Golden Slams—one in women's singles and two in women's doubles. In 2020, the Tennis Channel ranked her as the greatest women's tennis player of all time.