Serena William's pursuit of a calendar Grand Slam has stretched further as the women's semi finals at the US Open have been postponed due to heavy rain forecast. The matches will now take place later in the day. Williams will face Roberta Vinci after second seed Simona Halep meets Flavia Pennetta in the other semi final.The men's semi-finals will take place after the conclusion of the women's. Top seed Novak Djokovic faces defending champion Marin Cilic first, with second seed Roger Federer taking on his fellow Swiss Stan Wawrinka in the other match. The rainy conditions did not prevent the men's doubles semi-finals from going ahead as scheduled on Thursday.Great Britain's Dom Inglot and his partner Robert Linstedt were beaten 7-5 6-2 by French duo Nicolas Mahut and Pierre-Hugues Herbert, but Jamie Murray and his Australian partner John Peers won their semi-final later on. Murray and Peers saved a match point to beat Americans Steve Johnson and Sam Querrey 6-4 6-7 (2-7) 7-6 (9-7) and take their place in Saturday's final.