Marcelo is set to miss the Madrid derby between Real and Atletico after suffering a muscle injury during the team's shock defeat against Sevilla on Wednesday.
The Brazilian was substituted during the club's 3-0 loss in midweek, and medical tests have confirmed that he sustained a soleus injury.
Goal can confirm that the full-back will not play until after the international break, and will certainly miss this weekend's huge local derby.
The Brazil international has played only missed one La Liga game thus far this season - the 1-0 win over Espanyol earlier in the month - and has once again been a key figure at the back in the starting XI.
Real have won four, drawn one and lost one of their opening six La Liga encounters, and are level on points with Barcelona at the top of the table, who have also had a stuttering start to the 2018-19 campaign.
Julen Lopetegui's men are also top of their Champions League group, having beaten Roma 3-0 in their opening Group G encounter.
Atletico will provide Madrid with another stiff challenge this weekend and will be hoping to pick up an important three points themselves which could see them leapfrog their rivals in the league table.