UEFA is sending Italian refereeing great Pierluigi Collina to monitor Belgian match official Frank de Bleeckere's handling of a potentially volatile Champions League semifinals clash between Barcelona and Real Madrid UEFA has named Collina, its head of referees, as official observer at the Camp Nou on Tuesday. After Barcelona won a bad-tempered first leg 2-0, Madrid made a failed protest to UEFA about German referee Wolfgang Stark sending off Pepe when the game was scoreless. Collina was referee when the clubs last met in a Champions League semifinals, second-leg match. In 2002, the sides drew 1-1 in Madrid allowing Real to advance and win the title. Collina also refereed the 2002 World Cup final.