The Brazil international had picked up a thigh knock during his side's 3-1 over Anderlecht in the Champions League, adding to the catalogue of fitness problems that has hampered him in 2012.
“Pato is a problem,” Berlusconi told reporters.
“We really hope that he can fully recover from all these injuries. It is a problem because he was the one Milan player with the brightest future ahead of him.”
The former Prime Minister of Italy went on to say that his recent visits to the team have had a positive effect on the squad's results.
“I will be at Milanello tomorrow because Milan need me. Have you seen how the side become reinvigorated when I come here?
“There is a need for my presence and I will visit the squad at Milanello before the game against Juventus.”
The 76-year-old then went on to admit that he is sad that he no longer has Zlatan Ibrahimovic in the squad, but insisted that the Swede's sale to Paris Saint-Germain was necessary.
“I certainly have regrets that Ibrahimovic is not on the pitch, yet we have saved €160 million [£129m] over three years by selling him," he continued.
“But now we have [Stephan] El Shaarawy. Counting on youngsters is the right way forward.”