Tests carried out this morning have shown that Alexandre Pato and Pippo Inzaghi will not just miss this weekend's derby but also Milan's game against Fiorentina.
Both strikers limped off the pitch during last night's 3-1 victory over Palermo - Pato with a thigh strain and Inzaghi with a knee sprain.
The initial prognosis is worse than first thought as Milan will have to do without them at least until after November 20.
It's a bitter blow for Pato who will miss Brazil's friendly against Argentina in Doha on November 17.
The latest reports claim Inzaghi's season could even be at risk, as the injury has affected his meniscus and the ligaments around his knee.