LaLiga leaders Real Madrid have confirmed defender Pepe has sustained an injury to the calf muscle in his left leg.
The Portugal international last played in a 3-2 win over Deportivo La Coruna on December 10.
He travelled with the squad to Japan for the Club World Cup last month, but played no part as Zinedine Zidane's side defeated Club America and Kashima Antlers to lift the trophy.
And Pepe looks likely to miss at the least Madrid's Copa del Rey last-16 first leg against Sevilla on Wednesday after the European champions confirmed the 33-year-old's injury.