There are reports Gabriel suffered a serious injury, changing Milan’s transfer strategy around goalkeepers.
The 20-year-old Brazilian had overtaken Marco Amelia as second choice behind Christian Abbiati, but he has picked up a shoulder injury.
According to Sky Sport Italia, the injury could be serious and more tests will be needed next week.
With that in mind, Milan will abandon plans to sell Amelia and consider bringing in Ferdinando Coppola as third choice.
It would be a return for Coppola, who already wore the Rossoneri jersey in 2006-07, 2010-11 and 2012-13.
The 35-year-old would be available, as he is currently out of contract.