Serena Williams is the younger sister of former World number 1 Venus Williams. They have played each other in 23 professional matches since 1998, with Serena Williams winning 13 of these matches as of October 2009. As of July 2009, they have met in eight Grand Slam finals, with Serena Williams winning six times. Between the 2002 French Open and the 2003 Australian Open, they met in all four Grand Slam singles finals, the first time in the open era that the same two players had contested four consecutive Grand Slam finals. The pair have won 11 Grand Slam doubles titles together.
