Petra Kvitova has suffered an Australian Open setback, with the dual Wimbledon champion ruled out of the Hopman Cup with a foot injury.
Kvitova has been recovering from a stress fracture and needs more time to regain full health ahead of the season-opening grand slam at Melbourne Park.
"I am so disappointed I will be unable to play at the Hopman Cup. The results of an MRI have confirmed that my foot is healing but not as quickly as we would have liked," Kvitova said.
"The Hopman Cup is a fantastic event and I'm sorry I won't be able to represent my country in front of the great fans there."
Three-time doubles grand slam champion and two-time Olympic medallist Lucie Hradecka will replace the world No.11 for the Czech Republic at the Hopman Cup starting on New Year's Day.
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Hradecka will make her debut in Perth when she partners world No.75 Adam Pavlasek.
The pair will open the first day of play at the tournament against the United States' Jack Sock and Coco Vandeweghe.
Thirty-one-year-old Hradecka is an experienced doubles player who has won 21 doubles titles, including a US Open and French Open women's doubles title and a mixed title at Roland Garros.
In singles, her biggest win to date was against Ana Ivanovic in the first round of the Australian Open in 2015.
The right-hander has represented the Czech Republic at Fed Cup level since 2010 and in two Olympic Games. She holds one silver and bronze Olympic gold medal in women's doubles and mixed doubles.
Hopman Cup field (ATP and WTA rankings as of 20 December 2016):
Australia - 13-Nick Kyrgios and 25-Daria Gavrilova
Czech Republic - 75-Adam Pavlasek and 165-Lucie Hradecka
France - 18-Richard Gasquet and 42-Kristina Mladenovic
Germany - 24-Alexander Zverev and 55-Andrea Petkovic
Great Britain - 66-Daniel Evans and 76-Heather Watson
Spain - 28-Feliciano Lopez and 66-Lara Arruabarrena
Switzerland -16-Roger Federer and 43-Belinda Bencic
USA -23-Jack Sock and 36-Coco Vandeweghe
