Barcelona forward Ousmane Dembele is likely to be out for up to 10 weeks with a thigh injury, the club have confirmed.
The France international was forced off in the first half of Wednesday's 3-1 Champions League win over former club Borussia Dortmund.
Barca announced on Friday that Dembele has damaged his right hamstring and is expected to be out of action until February.
Dembele is due to miss a difficult run of matches for the LaLiga champions, who face Atletico Madrid, Real Mallorca, Real Sociedad, Real Madrid and Deportivo Alaves before the mid-season break.
He will also sit out the Champions League visit to Inter on December 10 and is highly likely to be unavailable for the revamped Supercopa de Espana, with Barca facing Atletico in the semi-final on January 8.
Dembele, who has started only three league games this season, has seen his Barca career blighted by injuries since he joined from Dortmund for an initial €105million.
The 22-year-old has had three previous thigh problems and twice damaged hamstrings, while he also suffered an ankle sprain in January.
Barca travel to Atleti on Sunday looking to secure their place at the top of the table.The champions are level on 28 points with Madrid after 13 games, with Atleti three points adrift of the leaders and one behind Sevilla.