Serena Williams is a golf player.
2009 WTA Tour Championships . Women 's Tennis Association ( WTA ) rank No. 2 Serena Williams won her second year-end championships title , defeating sister , Venus Williams in the final 6 -- 2 , 7 -- 6 ( 4 ) . The Grand Slam tournaments , also called majors , are the four most-important annual tennis events . Serena Jameka Williams ( born September 26 , 1981 ) is an American professional tennis player . She is also the most recent player , together with her sister Venus Williams , to have held all four Grand Slam women 's doubles titles simultaneously ( 2009 -- 10 ) .