Real Madrid have launched an enquiry into Robinho and Julio Baptista returning late from international duty with Brazil.
The pair missed training on Friday after their flight was delayed, and sat out Real's 2-1 defeat against Espanyol at the weekend.
Neither player informed the club they would be late back and Spanish media reports suggest they will be heavily fined.
"The board of directors are determined to speed up the enquiry and make their decision on the case as soon as possible," Real said in a statement on their official website.
Robinho was reportedly out partying in the early hours of Thursday morning after Brazil's 5-0 win over Ecuador in World Cup qualifying.
Meanwhile, Roberto Soldado has denied he wants to leave Real Madrid during the January transfer window.
The striker played the final 17 minutes against Espanyol and is keen to fight for regular playing time at the Santiago Bernabeu.
"I aspire for more minutes," Soldado told Spanish press. "I am 22-years-old and have plenty of time for success.
"In my head I only think of Real Madrid. I do not want to leave the club in January. My intention is to fight for a place in the 11."