Marcelo is set to be one of seven Real Madrid first-team players to miss the Champions League clash against Paris Saint-Germain on Wednesday.
The club announced that the defender suffered a "post-traumatic cervicodorsal injury" during Madrid's 3-2 victory over Levante on the weekend.
- ESPN Champions League fantasy: Sign up now!
Luka Modric, Isco, Federico Valverde and long-term absentee Marco Asensio missed the Levante match due to injuries, and all are expected to miss the trip to Paris as they did not feature during Monday's training session.
Club captain Sergio Ramos and Nacho are also ruled out of the PSG clash through suspension, so Zinedine Zidane will have to restructure his defence with summer signings Ferland Mendy and Eder Militao expected to start alongside Raphael Varane and Dani Carvajal.
Nacho was sent off during Madrid's 4-1 defeat by Ajax in last season's round of 16, while Ramos is completing a two-game ban "for clearly receiving a yellow card on purpose" during the first leg of that tie.
Since July 14, Brahim Diaz has been injured twice along with Asensio, Modric, Valverde, Ferland Mendy, Luka Jovic, Thibaut Courtois, Rodrygo, Eden Hazard, James Rodriguez and Isco.
There is some good news for Madrid as Gareth Bale is set to return after missing the Levante game through suspension.
The Wales international has impressed in the early stages of the season with two goals and one assist in four games.
Summer signing Eden Hazard is also set to feature on Tuesday after making his first appearance for Madrid on the weekend.