The Ghana international went under the knife last month after suffering a torn anterior cruciate ligament in his left leg while on holiday, with the Rossoneri stating that the 27-year-old would have to spend six months on the sidelines.
However, Muntari thinks that he will be able to return to action earlier than expected and says he wants to put this negative period behind him.
"I cannot wait to come back, everything is going well and even psychologically I am feeling good," he told Milan Channel.
"I have to be patient but everything is going well with the doctors...
"I do not think I will be out for too long, I will be back as soon as possible to help out my team-mates.
"We must win. I did not want to injure myself but these things happen in life and the injury is now a thing of the past."
Milan's chances of claiming the Scudetto have been written off in some quarters following the departures of Zlatan Ibrahimovic and Thiago Silva, but Muntari thinks that his side can go all the way.
"Last season we did not win the league but we must win it this term," he added. "I am observing the new arrivals and they are all working very hard and they are doing well.
"I have taken the No.4 shirt which belonged to Mark van Bommel. I like the number. At the end of the season I said to Mark that I wanted to take his number and he was happy. He encouraged me."
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