The United States became the first country to punch their ticket to the Davis Cup semi-finals on Saturday following a doubles win by Jack Sock and Ryan Harrison. The pair had to work for the victory on the hardcourts which gave the Americans an insurmountable 3-0 lead and a berth in the semis for the first time since 2012. Sock and Harrison needed three hours to dispatch Belgian debutants Sander Gille and Joran Vliegen in four sets 5-7, 7-6 (7/1), 7-6 (7/3), 6-4 in front of a crowd of 5,000 at the Curb Event Center in Nashville.