Marcelo trained away from the rest of the Real Madrid squad on Sunday, with the Brazilian's hamstring injury ruling him out of Tuesday's Champions League fixture against Club Brugge.
The left-back has now missed four Los Blancos fixtures, last featuring in the 3-2 victory over Levante on 14 September, and was unable to take part in training with his teammates.
According to Marca, Marcelo was involved in neither the light training for those who featured in Saturday's Madrid derby or the higher-intensity work with the rest of the squad.
Summer signing Ferland Mendy would have been hopeful of making a claim for Real's left back role in Marcelo's absence, but has picked up a muscle injury of his own to leave Zinedine Zidane short of options.
Nacho has deputised since and, despite putting in steady performances, just doesn't offer the same attacking threat as either Marcelo or Mendy.
There have been reports that Zidane might opt to play natural right back Alvaro Odriozola on the left against Brugge, after an impressive midweek performance against Osasuna in La Liga.
Whoever the Frenchman selects, he will be hopeful of picking up three points at Santiago Bernabeu. However, it might not be as easy as it appears on paper - Brugge are top scorers in the Belgian Pro League and might find a few heavy Real legs following the hard-fought draw with Atletico Madrid.
There are tougher tests on the horizon and the return of either first-team left back would certainly be welcome. Surprise second-place package Granada visit in La Liga next weekend, while there is an away fixture against Galatasaray before the big one - El Clasico at Barcelona's Camp Nou on 26 October.