- Top-seeded Czech Republic defeat Bulgaria in the Hopman Cup in Australia
- World number two Petra Kvitova beats Tsvetana Pironkova in straight sets
- Tomas Berdych seals Czech victory with success over Grigor Dimitrov
- World number one Caroline Wozniaki helps Denmark beat United States
Top seeds the Czech Republic opened their Hopman Cup campaign with a 2-1 Group A victory over Bulgaria on Monday.
World number two Petra Kvitova set the ball rolling in Perth with a 6-4 6-2 success over Tsvetana Pironkova, ranked 46th in the world.
And men's number seven Tomas Berdych secured the triumph by defeating Grigor Dimitrov 6-4 6-7 6-3.
Kvitova believes she will be under more pressure this year, after a remarkable 2011 which saw her win both Wimbledon and the WTA Tour Championships -- as well as leading the Czech Republic to their Fed Cup triumph.
"Every season is different. One year ago I was 34th in the world and now I am world ranked second." Kvitova told reporters after her victory.
"It is not always easy to play on the court and the first match of the year is always tough, but I played well."
The Bulgarian pairing earned a consolation by saving three match points to win the dead mixed-doubles rubber 2-6 6-3 11-9.
The later Group A match saw world number one Caroline Woznaicki help Denmark to a 2-1 victory over the United States.
Mardy Fish beat Frederik Nielsen 4-6 7-6 6-4 in the men's singles, but Wozniacki's 7-6 6-2 success over Bethanie Mattek-Sands drew the United States level.
However, the Danes secured victory when Wozniacki and Nielsen combined to beat the Americans 7-5 6-3.