Serena Jameka Williams is an American professional tennis player. The Women's Tennis Association ranked her world No. 1 in singles on eight separate occasions between 2002 and 2017. She reached the No. 1 ranking for the first time on July 8, 2002. On her sixth occasion, she held the ranking for 186 consecutive weeks, tying the record set by Steffi Graf for the most consecutive weeks as No. 1 by a female tennis player. In total, she has been No. 1 for 319 weeks, which ranks third in the Open Era among female players behind Graf and Martina Navratilova. Some commentators, players and sports writers regard her as the greatest female tennis player of all time. On April 19, 2017, she announced a hiatus from tennis until 2018 because of pregnancy.