Mascherano's absence is a significant blow to Ernesto Valverde, as it leaves the Barça coach short on cover for centre-backs Gerard Piqué and Samuel Umtiti, who are both one yellow card away from a suspension in LaLiga.
Mascherano doubtful for El Clásico on 23 December
'El Jefecito' is set to sit out the league games against Leganés, Valencia, Celta Vigo, Villarreal and Deportivo La Coruña, and faces a race against time to be fit for the week 17 clash with Real Madrid on 23 December.
Barça will also have to do without the 33-year-old for the remainder of the Champions League group stage, which sees the Catalans visit Juventus on 22 November and host Sporting CP on 5 December.
Valverde left with only Vermaelen as senior cover for Piqué, Umtiti
With Marlon Santos sent out on loan to Ligue 1 side Nice in the summer, the only other central defender in the first-team squad is Thomas Vermaelen, who has made just one appearance so far this season.