Ousmane Demeble has been ruled out for up to four months in an injury blow that has rocked Barcelona.

Dembele had to be withdrawn in the first half of his side's dramatic 2-1 victory at Getafe on Sunday (AEST), leaving the field after sustaining the problem while attempting a back-heel near the corner flag when the match was still goalless.

"Unfortunately, he has ruptured the tendon in his femoral bicep in his left thigh," a statement from Barccelona read.

"The player will be operated on by Dr. Sakari Orava in Finland this week. He is expected to be out for between three and a half to four months."

Barca coach Ernesto Valverde had feared the worst when he spoke of the injury in the wake of the win over Getafe.

"He is going to have to spend some time on the sidelines," Valverde said after the match.

"It is a muscle problem. We think it is a tear, but we will do more tests.

"It is a shame because he was just getting up to scratch with the team's dynamic. We hope he won't be out for a long time." 

Barca, which has won all four of its LaLiga matches to start the new season, has clashes against Eibar, Girona, Sporting CP and Las Palmas before the next international break, after which it is away to Atletico Madrid on 15 October (AEST).

Signed for an initial €105 million ($156.6 million), ex-Borussia Dortmund winger Dembele had made his first Barca start against Juventus in the UEFA Champions League on Wednesday (AEST), having come on as a substitute at home to Espanyol last week, his first game in the club's colours.