Andy Murray of Britain reacts against Grigor Dimitrov of Bulgaria in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, 25 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/Filip Singer

Eugenie Bouchard of Canada in action against Irina-Camelia Begu of Romania in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, 25 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/Narendra Shrestha

Nick Kyrgios of Australia picks up his racket after smashing it against Andreas Seppi of Italy in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, 25 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/MADE NAGI

Rafael Nadal of Spain in action against Kevin Anderson of South Africa in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, 25 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/Narendra Shrestha

Maria Sharapova of Russia reacts against Peng Shuai of China in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, 25 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/Filip Singer

Grigor Dimitrov of Bulgaria holds his broken racket after smashing it on the ground against Andy Murray of Britain in their fourth round match at the Australian Open Grand Slam tennis tournament in Melbourne, Australia, early 26 January 2015. The Australian Open tennis tournament runs from 19 January until 01 February 2015. EPA/Narendra Shrestha