Real Madrid defender Marcelo is reportedly targeting a return to full fitness for the local derby against Atletico Madrid at the end of the month.
The 27-year-old dislocated his shoulder after landing awkwardly late on in the 2-1 win over Granada at Los Carmenes on 7 February.
Spanish daily AS said the injury will likely force the defender to miss Real's Champions League round of 16 trip to Roma on 17 February, and that he was targeting a return to action in the Atletico match ten days later.
The paper said the injury was not as serious as the shoulder problems that plagued Real captain Sergio Ramos earlier in the season.
A statement released by Real on 9 February read: "After tests carried out today on the player Marcelo at the Sanitas La Moraleja University Hospital, he has been diagnosed with acromioclavicular shoulder joint dislocation. His recovery will continue to be assessed."
Spain international Nacho is likely to deputise at left-back in Marcelo's absence, while veteran defender Alvaro Arbeloa is another possibility.
Real are also likely to be without Gareth Bale for the crucial Roma match, after the Wales forward aggravated his calf injury by training on a sand pitch at the club's training ground.
The 26-year-old, who has scored 13 goals in 15 league appearances for Madrid this season, suffered the injury in the 5-1 win over Sporting Gijon on 17 January.
The injuries come at an inopportune time for Real, with the Champions League increasingly being seen as the club's best shot at winning a major title this season.
Zidane's men are four points behind La Liga leaders Barcelona, who have two games in hand. They were thrown out of the Copa del Rey in December for fielding an ineligible player.
The club's next assignment is a league fixture against Athletic Bilbao at the Santiago Bernabeu on 13 February.