The 32-year-old played all 90 minutes of last night’s 3-0 defeat at Juventus but has now picked up a problem, although there is no indication yet of how long he might be out for.
"The first team player Javier Mascherano has a problem with his left calf and his recovery will determine when he will be available once again," the club said in a brief statement.
The news will be a further blow to Barcelona who are already without Neymar for Saturday’s game after he was hit with a three-game ban following his sending off at Malaga.
There was some slightly better news for Luis Enrique’s side however, with Arda Turan back in training after an injury lay-off although he still may not be ready in time for Sociedad.
"Arda Turan was able to work out with his colleagues, though he has not yet been declared fully fit after picking up a groin injury on international duty for Turkey," said the club.
Barcelona welcome Sociedad to Camp Nou on Saturday on the back of two straight defeats and knowing they can ill-afford to drop any more points if they are to have any chance of pipping Real Madrid to the title.