The defender was part of the starting XI for Milan in the match at San Siro, but picked up a knock in the first half and remained in the dressing room at half-time.
Bonera was taken to the hospital after his substitution to undergo further examination, and Milan have now stated that he has sustained a head injury.
"Daniele Bonera suffered a slight head trauma and a whiplash. His recovery time will be evaluated over the next few days. The player has already returned home," a statement on the club's official website reads.
Milan climbed to third spot in the Serie A table following Sunday's home victory and have now collected 20 points from 10 games.
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