Barcelona could be without goalkeeper Marc-Andre ter Stegen against Espanyol on Saturday.
Marc-Andre ter Stegen is a doubt for Barcelona's next LaLiga meeting with Espanyol, while Arthur will not return in time for the Supercopa de Espana.
Goalkeeper Ter Stegen is undergoing treatment on a tendon problem in his right knee and was declared "unavailable" by Barca on Monday, five days before they return to action against their local rivals.
While no time frame for the Germany international's return to action was provided by the club, they did confirm Arthur will be missing for another three weeks.
The midfielder has been out of action since sustaining a groin injury in the 1-0 victory over Atletico Madrid on December 1.
Arthur will miss Barca's trip to Saudi Arabia, where they face Atletico in the Supercopa de Espana semi-finals on January 9.
He could return for the visit to Mestalla to face Valencia on January 25.