Vinicius, 18, completed a £40m switch to the European champions from Flamengo in the off-season and was widely expected to become a backup player for the first-team.
However, the club have taken the stance of sending him to play with their Castilla side, where he's netted three goals in as many games.
The Brazil youth international has broken Real Madrid TV viewing records with his presence in the third-tier of Spanish football - while also being banned from speaking to the press.
And this has left former FC Barcelona forward Rivaldo bewildered.
"I do not understand why he plays in the reserves," Rivaldo said in an interview with Betfair.
"He is competing in a league lower than his level, with all due respect he is above his teammates and opponents in Segunda B."