Spain's Rafael Nadal returns a ball to Argentina's Juan Martin Del Potro during the Davis Cup final fourth match at La Cartuja Olympic stadium in Sevilla on December 4, 2011. AFP PHOTO/JAVIER SORIANO
Argentina's Juan Martin Del Potro celebrates winning a point against Spain's Rafael Nadal during the Davis Cup final fourth match at La Cartuja Olympic stadium in Sevilla on December 4, 2011. AFP PHOTO/JAVIER SORIANO
Spain's Rafael Nadal returns the ball to Argentina's Juan Martin Del Potro during their Davis Cup final reverse singles rubber at the Olympic Stadium in Seville December 4, 2011. REUTERS/Javier Diaz (SPAIN - Tags: SPORT TENNIS)