Mogadishu: The United States opened their Hopman Cup campaign with a 3-0 win over the Czech Republic in Perth on Sunday. The American pair of Jack Sock and Coco Vandeweghe won both their singles matches to clinch the tie, and then made it a clean sweep with victory in the mixed doubles. After Vandeweghe beat Lucie Hradecka 6-4, 6-2 to open the tie, Sock then edged past Adam Pavlasek in three sets. The mixed doubles rubber was a relaxed affair and the US came from a set down to win 2-4, 4-2, 4-1.