Sam Groth of Australia throws his racquet after losing a point to Milos Raonic of Canada during their men's singles quarter final at the Brisbane International tennis tournament January 9, 2015. (Photo by Jason Reed/Reuters)

Milos Raonic of Canada watches the ball as he returns to Sam Groth of Australia during their men's singles quarter final at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Sam Groth of Australia celebrates winning the second set of his men's singles quarter final against Milos Raonic of Canada at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Kei Nishikori of Japan delivers a backhand return to Bernard Tomic of Australia during their men's singles quarter final at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia reacts after winning a point against Varvara Lepchenko of the United States during their women's singles semi final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia speaks with her coach Dejan Petrovich between games against Varvara Lepchenko of the U.S. during their women's singles semi final match at the Brisbane International tennis tournament January 9, 2015. (Photo by Jason Reed/Reuters)

Varvara Lepchenko of the U.S. drops her racquet after losing a point during her women's singles semi final match against Ana Ivanovic of Serbia at the Brisbane International tennis tournament January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia celebrates a point during her women's singles semi-final win against Varvara Lepchenko of the U.S. at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia serves to Varvara Lepchenko of the U.S. in their women's singles semi final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia reacts as she waits for a line call during her women's singles semi-final win against Varvara Lepchenko of the U.S. at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia laughs as she slips on the court following a return shot to Varvara Lepchenko of the U.S. during their women's singles semi final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia plays a backhand return in the afternoon light during her women's singles semi-final match against Varvara Lepchenko of the U.S. at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Roger Federer of Switzerland plays a backhand return to James Duckworth of Australia in their men's singles quarter-final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

James Duckworth of Australia (R) walks off the court after losing in straight sets to Roger Federer of Switzerland (L) in their men's singles quarter-final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

James Duckworth of Australia plays a return to Roger Federer of Switzerland during their men's singles quarter-final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Heather Watson of Britain plays a backhand shot to Casey Dellacqua of Australia during their women's singles tennis match at the 2015 Hopman Cup in Perth, January 9, 2015. (Photo by Reuters/Stringer)

Maria Sharapova of Russia wins a point during her women's singles semi final match against Elina Svitolina of Ukraine at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Maria Sharapova of Russia wins a point during her women's singles semi final match against Elina Svitolina of Ukraine at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Maria Sharapova of Russia blows a kiss to fans after defeating Elina Svitolina of Ukraine in their women's singles semi final match at the Brisbane International tennis tournament in Brisbane, January 9, 2015. (Photo by Jason Reed/Reuters)

Andy Murray of Britain serves to Marinko Matosevic of Australia during their men's singles tennis match at the 2015 Hopman Cup in Perth, January 9, 2015. (Photo by Reuters/Stringer)

Spain's David Ferrer returns the ball to Croatia's Ivo Karlovic during their semi-final tennis match at the Qatar Open tennis tournament in Doha January 9, 2015. (Photo by Mohammed Dabbous/Reuters)

Andy Murray of Britain reacts after losing a point against Marinko Matosevic of Australia during their men's singles tennis match at the 2015 Hopman Cup in Perth, January 9, 2015. (Photo by Reuters/Stringer)

Spain's David Ferrer reacts against Croatia's Ivo Karlovic during their semi-final tennis match at the Qatar Open tennis tournament in Doha January 9, 2015. (Photo by Mohammed Dabbous/Reuters)

David Ferrer of Spain celebrates after winning his semi-final match against Croatia's Ivo Karlovic at the Qatar Open tennis tournament in Doha January 9, 2015. (Photo by Mohammed Dabbous/Reuters)

Tomas Berdych of the Czech Republic serves to Italy's Andreas Seppi during their semi-final match at the Qatar Open tennis tournament in Doha January 9, 2015. (Photo by Mohammed Dabbous/Reuters)

Kei Nishikori of Japan uses an ice towel between games during his men's singles semi final match against Milos Raonic of Canada at the Brisbane International tennis tournament, January 10, 2015. (Photo by Jason Reed/Reuters)

Kei Nishikori of Japan wins a point against Milos Raonic of Canada during their men's singles semi final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Roger Federer of Switzerland serves during his men's singles semi final win over Grigor Dimitrov of Bulgaria at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia plays a backhand return to Maria Sharapova of Russia during their women's singles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Roger Federer of Switzerland wipes his brow in the afternoon sun during his men's singles semi final win over Grigor Dimitrov of Bulgaria at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Serena Williams of the U.S. plays a forehand shot to Agnieszka Radwanska of Poland during their women's singles tennis final at the 2015 Hopman Cup in Perth January 10, 2015. (Photo by Reuters/Stringer)

Ana Ivanovic of Serbia reacts to a lost point early in her women's singles final match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia bites her racquet after losing a point during her women's singles final match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia wins a point in the during her women's singles final match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia dives for a shot at the baseline during her women's singles final match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Ana Ivanovic of Serbia sits on the court after missing a shot during her women's singles final match against Maria Sharapova of Russia at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Maria Sharapova of Russia holds the Brisbane International tennis tournament women's singles trophy after defeating Ana Ivanovic of Serbia in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Maria Sharapova of Russia (L) holds the Brisbane International tennis tournament women's singles trophy after defeating Ana Ivanovic of Serbia (R) in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Jerzy Janowicz of Poland plays a backhand shot to John Isner of the U.S. during their men's singles tennis final at the 2015 Hopman Cup in Perth January 10, 2015. (Photo by Reuters/Stringer)

Maria Sharapova of Russia (L) meets Ana Ivanovic of Serbia at the net after Sharapova won their women's singles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Martina Hingis (L) of Switzerland and Sabine Lisicki of Germany prepare to receive their trophy after winning the women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. The pair defeated Caroline Garcia of France and Katarina Srebotnik of Slovenia to win the title. (Photo by Jason Reed/Reuters)

Maria Sharapova of Russia holds the Brisbane International tennis tournament women's singles trophy after defeating Ana Ivanovic of Serbia in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Martina Hingis (L) of Switzerland and Sabine Lisicki of Germany hold their trophy after winning the women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Martina Hingis of Switzerland and Sabine Lisicki (facing camera) of Germany embrace after winning the women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Agnieszka Radwanska and Jerzy Janowicz of Poland kiss the Hopman Cup after defeating Serena Williams and John Isner of the U.S. in the 2015 Hopman Cup final in Perth, January 10, 2015. (Photo by Reuters/Stringer)

Agnieszka Radwanska and Jerzy Janowicz of Poland celebrate after defeating Serena Williams and John Isner of the U.S. in the 2015 Hopman Cup final in Perth, January 10, 2015. (Photo by Reuters/Stringer)

Jerzy Janowicz (L) and Agnieszka Radwanska of Poland celebrate after defeating Serena Williams and John Isner of the U.S. in the 2015 Hopman Cup final in Perth, January 10, 2015. (Photo by Reuters/Stringer)

Agnieszka Radwanska (R) and Jerzy Janowicz of Poland hold up the Hopman Cup after defeating Serena Williams and John Isner of the U.S. in the 2015 Hopman Cup final in Perth, January 10, 2015. (Photo by Reuters/Stringer)

Martina Hingis (L) of Switzerland and Sabine Lisicki of Germany embrace after winning their women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Martina Hingis (L) of Switzerland and Sabine Lisicki (2nd R) of Germany meet their opponents Caroline Garcia (L) of France and Katarina Srebotnik of Slovenia at the net after winning the women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Martina Hingis (R) of Switzerland and Sabine Lisicki of Germany celebrate after winning the women's doubles final match at the Brisbane International tennis tournament in Brisbane, January 10, 2015. (Photo by Jason Reed/Reuters)

Spain's David Ferrer celebrates after winning his Qatar Open Men's Singles Final tennis match against Tomas Berdych of the Czech Republic in Doha January 10, 2015. (Photo by Mohammed Dabbous/Reuters)