The United States pairing of Serena Williams and John Isner snuck into the Hopman Cup final with a 3-0 win over the Czech Republic at the Perth Arena on Thursday. The pre-tournament favourites had to complete a clean sweep of the Czech combination of Lucie Safarova and Adam Pavlasek in the Group A tie to reach Saturday's final of the mixed teams tournament. Having won both singles matches, Williams and Isner powered on through, taking the mixed doubles in straight sets, 6-3, 6-3.