Fiorentina have suffered a double injury setback after both Mario Gomez and Juan Cuadrado were hurt in Sunday's 1-1 draw with Cagliari.
The German striker, who arrived from Bayern Munich for 20million euros, was carried off the Stadio Artemio Franchi pitch after taking a shot early in the second half.
Medical examinations have revealed a sprain to the 28-year-old's right knee, with a statement on Fiorentina's official website confirming "a partial tear in the medial collateral ligament."
Colombian winger Cuadrado, 25, was also withdrawn injured and has suffered a dislocated shoulder "without fracture."
Further tests will be carried out over the coming days but Gomez can expect to miss at least six weeks of action while Cuadrado is set for a two-week spell on the sidelines.
Midfielder David Pizarro is also ruled out of next week's Serie A trip to Atalanta after picking up a red card for insulting the referee towards the end of Sunday's draw.
The points dropped against Cagliari ruined Fiorentina's 100 per cent start to the new season, which started with wins over Catania and Genoa.