Ignazio Abate will undergo tests on Tuesday after the Milan man picked up an ankle problem in the loss to Juventus.
The right-back, replaced by Antonio Nocerino after 50 minutes in the 3-2 loss to Juventus on Sunday, twisted his right ankle during the game.
The former Torino player will have the injury assessed tomorrow morning when he and the rest of the side return to training.
Milan open their campaign with a home game against Sampdoria at the weekend.
Tickets for the Champions League final between Juventus and Real Madrid are still on sale with reseller Viagogo - Click to find out more