The newspaper La Voz de Galicia reports that an X-ray examination confirmed a muscle tear and tendon damage in one thigh.
Celta Vigo also confirmed that Starfelt will be out for about six weeks.
This means the 31-year-old looks set to miss Sweden's final two Nations League matches, against Bosnia and Herzegovina on November 14 and Poland on November 17.
Starfelt was forced off early in Friday's match against Bosnia and Herzegovina, in which he started. Eric Smith has since taken his place alongside captain Victor Nilsson Lindelöf in central defence.
Sweden tops the B division with 10 points from four matches.
