Novak Djokovic of Serbia hits a return to Stan Wawrinka of Switzerland during their men's singles semi-final match at the Australian Open 2015 tennis tournament in Melbourne January 30, 2015. ... more 
Novak Djokovic of Serbia hits a return to Stan Wawrinka of Switzerland during their men's singles semi-final match at the Australian Open 2015 tennis tournament in Melbourne January 30, 2015. REUTERS/Carlos Barria (AUSTRALIA - Tags: SPORT TENNIS) less 
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Reuters | Photo By CARLOS BARRIA / REUTERS
Fri, Jan 30, 2015 6:32 AM EST