Juventus defender Zdenek Grygera will be out for five weeks after scans confirmed he had sustained ligament damage in his knee.
The 30-year-old picked up the injury against Red Bull Salzburg in the Europa League match in midweek.
Grygera will begin his rehabilitation work within the next few days but it could take up to five weeks before he is fit and available for selection for the Turin giants.
His absence could create a defensive headache for coach Luigi Del Neri as the Czech international can play either at centre or right-back.
Juventus are currently third in Europa League Group A after three games and fifth in Serie A.