World number one and defending champion Serena Williams defeated her sibling Venus Williams to enter the semi finals of the US Open Tennis Tournament. In a quarter final match concluded a short while ago, 21 times Grand Slam winner Serena beat sister Venus 6-2, 1-6, 6-3. India's Sania Mirza along with her Swiss partner Martina Hingis have entered semi-finals of women's double event. In the quarter finals, top seeded Indo-Swiss duo defeated Chinese Taipei pair of Yung-Jan Chan and Hao-Ching Chan in straight sets 7-6, 6-1. For a place in finals the Wimbledon winning pair will be meeting 11th seed Italian pair of Sara Errani and Flavia Pennetta in the evening.In the men's singles event, defending champion Marin Cilic have entered the semi finals after beating French Jo Wilfried Tsonga. In a long five setter game of quarter finals, Croatian Cilic recorded victory over 19th seed Tsonga 6-4, 6-4, 3-6, 6-7, 6-4. Meanwhile, later in the evening India's Leander Paes and Rohan Bopanna will face each other in the semi finals of the mixed doubles event. Later, Bopanna will also be seen in quarter finals of men's doubles.