Tennis and running are set to be the big Olympic sports of the day, and the Williams sisters are the day's early stars. In a repeat of 2000 and 2008, Serena and Venus took the women's doubles gold, beating Andrea Hlavackova and Lucie Hradecka of the Czech Republic 6-4, 6-4. Venus closed out the match with a backhand volley winner after the Czechs saved a pair of match points, reports the AP. Serena won her first singles gold yesterday. Up next, tennis-wise: Roger Federer and Andy Murray face off in the men's gold medal match.