Perth - Nick Kyrgios has withdrawn from the Australian team at the Hopman Cup because of a back injury and has been replaced by Matthew Ebden.
Kyrgios, who beat Rafael Nadal in the fourth round at Wimbledon in July, also planned to play in the Sydney International before the Australian Open begins on January 19, but this is now uncertain.
Ebden will be partnered by Casey Dellacqua in the Hopman Cup mixed teams event in Perth, tournament officials said Thursday.
Australia open play on Sunday against Poland, with Canada earlier taking on Czech Republic.
Americans Serena Williams and John Isner will play their first match Monday against Italy.