Canada's fans cheer during the Davis Cup semi-final tennis match between Serbia's Novak Djokovic and Canada's Vasek Pospisil in Belgrade September 13, 2013.MARKO DJURICA/Reuters
Canada's Vasek Pospisil returns the ball to Serbia's Novak Djokovic during their Davis Cup semi-finals tennis match in Belgrade, Serbia, Friday, Sept. 13, 2013.Marko Drobnjakovic/The Associated Press
Serbia's Novak Djokovic clinches his fist as he celebrates a point won against Canada's Vasek Pospisil during their Davis Cup semi-finals tennis match in Belgrade, Serbia, Friday, Sept. 13, 2013.Marko Drobnjakovic/The Associated Press
Canada's Vasek Pospisil returns the ball to Serbia's Novak Djokovic during their Davis Cup semi-final tennis match in Belgrade September 13, 2013.MARKO DJURICA/Reuters
Serbia's Novak Djokovic fails to return the ball to Canada's Vasek Pospisil during their Davis Cup semi-finals tennis match in Belgrade, Serbia, Friday, Sept. 13, 2013.Marko Drobnjakovic/The Associated Press
Serbia's Novak Djokovic returns the ball to Canada's Vasek Pospisil during their Davis Cup semi-final tennis match in Belgrade September 13, 2013.MARKO DJURICA/Reuters
Serbia's Novak Djokovic celebrates after winning a point against Canada's Vasek Pospisil during their Davis Cup semi-final tennis match in Belgrade September 13, 2013.MARKO DJURICA/Reuters
Serbia's Novak Djokovic celebrates his victory over Canada's Vasek Pospisil after their Davis Cup semi-final tennis match in Belgrade September 13, 2013.Reuters
Canada's Milos Raonic returns the ball to Serbia's Janko Tipsarevic during their Davis Cup semi-final tennis match in Belgrade September 13, 2013.Reuters
Serbia's Janko Tipsarevic returns the ball to Canada's Milos Raonic during their Davis Cup semi-final tennis match in Belgrade September 13, 2013.Reuters
Canada's Milos Raonic, centre, celebrates his victory over Serbia's Janko Tipsarevic with his team after their Davis Cup semi-final tennis match in Belgrade September 13, 2013.Reuters
Milos Raonic of Canada celebrates after their Davis Cup semi-final tennis match against Janko Tipsarevic of Serbia, in Belgrade, Serbia, Friday, Sept. 13, 2013.The Associated Press
Argentina's Juan Monaco reacts during the Davis Cup semi-final tennis match against Czech Republic's Radek Stepanek in Prague September 13, 2013.PETR JOSEK/Reuters
Czech Republic's Radek Stepanek celebrates after winning the first set over Argentina's Juan Monaco during their Davis Cup semi-final tennis match in Prague September 13, 2013.DAVID W CERNY/Reuters
Argentina's Juan Monaco returns the ball to Czech Republic's Radek Stepanek during their Davis Cup semi-final tennis match in Prague September 13, 2013.DAVID W CERNY/Reuters
Czech Republic's Radek Stepanek celebrates after winning over Argentina's Juan Monaco during their Davis Cup semi-final tennis match in Prague September 13, 2013.DAVID W CERNY/Reuters
Czech Republic's Tomas Berdych watches a ball as he falls during his Davis Cup semi-final tennis match against Argentina's Leonardo Mayer in Prague, September 13, 2013.Reuters
Spain's Fernando Verdasco returns a shot to Ukraine's Alexandr Dolgopolov during their Davis Cup World Group playoff tennis tie in Madrid September 13, 2013.SERGIO PEREZ/Reuters
Ukraine's Alexandr Dolgopolov returns a backhand to Spain's Fernando Verdasco during their Davis Cup World Group playoff tennis tie in Madrid September 13, 2013.SERGIO PEREZ/Reuters
Spain's Rafael Nadal reaches out to return a shot to Ukraine's Sergiy Stakhovsky during their Davis Cup World Group playoff tennis tie in Madrid September 13, 2013.Reuters