The defender was substituted during the club's 3-0 loss in midweek, and medical tests have confirmed that he sustained a soleus injury.
Reports suggest he will not return until after the international break, and will certainly miss this weekend's local derby against Atletico.
The 30-year-old was recalled to the Brazil squad for October’s Brasil Global Tour of Saudi Arabia after missing out on coach Tite’s first post-World Cup squad.
However, having been a guaranteed starter for the first two years of Tite’s Brazil reign, the Madrid man is now facing a battle to regain his place at left-back after Juventus’ Alex Sandro impressed in September.
Marcelo returned to the Brazil squad at the expense of Atletico’s Filipe Luis, who will now be hoping for an international recall in the coming days.
Brazil meet Saudi Arabia at King Saud University in Riyadh on October 12 before meeting Argentina at King Abdullah Sports City in Jeddah on October 16.