The Wimbledon tennis champion Petra Kvitova and team-mate Tomas Berdych won their singles matches in straight sets to lead the Czech Republic to a 3-0 win over the United States at the Hopman Cup.
Kvitova opened with a 6-2 6-1 victory over Bethanie Mattek-Sands and Berdych beat Mardy Fish 6-3 6-3.
Berdych saved four break points while serving for the match before converting his first match point to ensure the Czechs won their second straight match at the eight-country tournament.
Berdych and Kvitova made it a clean sweep when they beat Mattek-Sands and Fish 6-3 7-5 in mixed doubles.
The extra point that the winners earned could help determine the final placings in Group A, where the Czechs are strong favourites to qualify for Sunday's final.
The Americans, who have won the Hopman Cup a record six times, fell to 0-2 after losing to Denmark in their opening match.