Brazil coach Dunga has vowed to reveal the truth over his decision to leave Real Madrid defender Marcelo out of his squad for the matches against Uruguay and Paraguay.

Dunga somewhat surprisingly omitted the 27-year-old for both World Cup qualifiers, supposedly for fitness reasons with the left-back missing a number of games in recent weeks due to minor physical problems.

Madrid, who face Barcelona in the season's second El Clasico next weekend, denied they did not want the defender to travel to Brazil for the matches with the player admitting the situation "bothered him a little bit".

"After these two games, the Brazil doctor will show the messages that were exchanged [with Madrid's medical staff]," Dunga said at a news conference.

"We will reveal the truth after the game against Paraguay."

Brazil sit fifth in the table ahead of Friday's match against Uruguay with seven points from four games, with Uruguay second on nine points.