Diego Simeone's Madrid side have been dealt a huge injury blow as it has been confirmed that full-back Filipe Luis suffered a hamstring injury following their Champions League clash with Qarabag.
The Brazillian left-back played all 90 minutes of the 1-1 draw but did not participate in training the following day.
He was later diagnosed with a hamstring injury, sidelining him for an undisclosed period of time.
Atletico face the potential of being eliminated from the group stages of the Champions League, which would be a significant blow for Simeone's men, considering they have appeared in two of the last four finals.
The 32-year-old was a staple in Simeone's defensive line, and his absence could spark trouble for Atleti, as they will be facing Real Madrid, Roma and Chelsea, within the next month.
The Argentinian manager will look to shuffle Juanfran over to cover the left-back position, but the absence of Luis will also have an effect on Atleti's La Liga challenge as they fallen down to fourth in the table, behind, Real, Valencia and Barcelona.
The Red and White side of Madrid would not want to endure another trophy-less season as rumours surrounding the departure of Antoine Griezmann have been ever-present.
Failure to qualify for the knockout stages could tempt the French Starlet to take his talents elsewhere, therefore, Atletico will find it essential to grind out results, in order to keep Griezmann in the Spanish capital.
Atletico's next Champions League game is against group leaders Rome, with them needing a win to keep the hopes of qualification alive.
Failure to qualify for the round of 32 will see Atletico fall into the Europa League.