Overview:Coverage as Manchester United open their challenge for the Club World Championship at the Maracana Stadium in Rio de Janeiro. United had unprecedented domestic and European success last season and recently became the first British club to win the World Club Cup. Their opponents tonight are the Mexican Concacaf Champions' Cup winners Necaxa. With an average age of over 30, they may be heading into their final season as a strong force, but they do boast the Champions' Cup top scorer Agustin Delgado.