Barcelona forward Ousmane Dembele will be out for up to four months with a hamstring injury.
The club's record signing, who joined from Borussia Dortmund in a deal which could be worth £135.5m, hobbled off during Saturday's win over Getafe.
A statement on the club's website said the 20-year-old France international had ruptured "his tendon in the femoral bicep in his left thigh".
It added Dembele will have surgery in Finland this week.
"He is expected to be out for between three and a half months and four months," said the statement.
Dembele was making his first league start for Barcelona and his third overall.
He came on as a substitute in a 5-0 league win over Espanyol, started the 3-0 Champions League victory over Juventus on Tuesday and lasted 29 minutes against Getafe.
Dembele will miss France's final two World Cup qualifiers away to Bulgaria and at home to Belarus in October.