MADRID, Jan. 16 (Xinhua) -- FC Barcelona have confirmed that Ousmane Dembele has suffered a further injury problem and will be out of action for between three weeks and a month.

Dembele had only recently returned to the side on January 4th after three and a half months out with a leg injury which had required an operation in Finland.

The new injury is a torn muscle in his left thigh, which he suffered while playing as a substitute in the second half of Sunday's 4-2 win away to Real Sociedad.

The club confirms that if his new recovery goes to plan the Frenchman should be fit for the first leg of the Champions League tie which sees Barcelona play English Champions, Chelsea.

However, he will miss at least three Liga Santander games, the quarter-finals of the King's Cup against local rivals, Espanyol and the semi-finals if Barca are able to beat their local rivals.

Barca also have a further injury worry for Wednesday's Cup tie as midfielder Andres Iniesta is struggling with a minor problem in his right calf. Iniesta was on the bench at the weekend, but didn't get into the action or even warm up as Barca came back from 2-0 down to eventually triumph 4-2.

Meanwhile recent signing Phillipe Coutinho is two weeks away from making his debut after his big-money arrival from Liverpool. The Brazilian has a hamstring problem and won't play before the start of February.