Ousmane Dembele has been ruled out for the next four weeks with a left hamstring problem, with Barcelona saying the injury has nothing to do with the surgery he underwent earlier in the season.
Dembele, 20, joined Barca from Borussia Dortmund last summer for an initial fee worth €105 million but ruptured a tendon in just his third appearance for the club in September.
The France international resumed training in December and then returned earlier this month as a second-half substitute in the Copa del Rey game at Celta Vigo.
He then started Barca's league win over Levante and came on as a substitute in the return leg against Celta and against Real Sociedad on Sunday, when he sustained his latest injury.
"After the game against Real Sociedad, Dembele had a problem with his left thigh and tests have confirmed that the player has suffered a hamstring injury, although it does not affect the area operated on earlier in the season," Barca said in a statement.
"The injury will mean he will be out for a period of around three to four weeks."
Dembele, who has made just seven appearances for Barca in total, will miss the Copa del Rey doubleheader against city rivals Espanyol and next week's trip to Real Betis in the league.
Ernesto Valverde will also be without the forward -- who was replaced by Philippe Coutinho last week as the club's record signing -- for league games against Alaves, Espanyol and Getafe as well as any potential Copa del Rey semifinal.
Barca will hope to have him back for the trip to Eibar in the middle of February, which precedes their trip to Chelsea in the Champions League.
Andres Iniesta, meanwhile, who was an unused substitute at Anoeta on Sunday, is suffering from a calf problem and is a doubt for Wednesday's derby at Espanyol.
"Iniesta has a problem in his right calf and his recovery will determine his return to action for the coming matches," the club said.
Samuel Umtiti and Paco Alcacer are both back in training, though, and should be able to make their return to action in the coming weeks.
Elsewhere, Nelson Semedo remains at home recovering from tonsillitis, which kept him out of action against Real Sociedad. It's not clear when he will be able to return to training with the first team.