The Paris Saint-Germain defender is in awe of the quality of la Roja's reserves, arguing they are just as strong as those starting ahead of them
La Roja go into the game in Rio hoping to complete their international set, having won their last three major tournaments: Euro 2008, World Cup 2010 and Euro 2012.
And he claims that Vicente del Bosque is effectively in possession of two separate sets of players capable of winning the World Cup.
"We will face a team of great quality," the Paris Saint-Germain defender admitted. "They have a squad made up of reserves that are of the same level as the starters, a group that are world champions."
However, while Thiago Silva has nothing but respect and admiration for Spain's achievements, and the way in which they play the game, he is in no doubt that the Selecao can push la Roja right to the limit in Rio.
"We are well prepared to challenge Spain," the centre-half declared. "I think that this game will be decided only by little details."
Brazil are bidding to win their third successive Confederations Cup - and their fourth overall.