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.