Williams sisters, Nadal through 4th round at U.S. Open

Serena Williams from the United States celebrates her victory over France's Severine Bremond after the 4th round of the women's singles at the US Open 2008 in New York, the United States, Sept. 1, 2008. Serena Williams won 2-0

Venus Williams of the United States returns a shot during the 4th round of the women's singles event against Agnieszka Radwanska of Poland at the US Open 2008 held in New York, the United States, Sept. 1, 2008. Venus Williams won the match 2-0 and advanced to the next round.