Serena Williams plays tennis.
Serena Williams . In total , she has been world no. 1 for 319 weeks , which ranks her third in the Open Era among female tennis players . Williams ' accomplishments and success in professional tennis have led some commentators , players , and sports writers to regard her as the greatest female tennis player of all time . Her total of 23 Grand Slam singles titles marks the record for the most Grand Slam wins by a tennis player in the Open Era , and is second on the all-time list behind Margaret Court ( 24 ) . She is the only tennis player in history ( man or woman ) to have won singles titles at least six times in three of the four Grand Slam tournaments , and the only player ever to have won two of the four Grand Slams seven times each ( seven Wimbledon titles and seven Australian Open titles ) . She is also the only tennis player to have won 10 Grand Slam singles titles in two separate decades .