AC Milan forward Antonio Cassano underwent a successful minor heart surgery Friday, the club said.

"Antonio Cassano is well and over the next few days he'll undergo tests which will determine his release date," from the hospital, Milan said in a statement.

Milan vice-president Adriano Galliani has said Cassano could be out from four to six months.

The procedure to close a small opening in the Italy international's heart was carried out by Dr. Mario Carminati at the Maggiore hospital, with Milan physician Rodolfo Tavana also present.

Milan announced Wednesday that Cassano has a cardiac anomaly which caused a brain problem due to impaired blood flow.

The 29-year-old Cassano has been hospitalized since Saturday, when he was taken for tests after falling ill on the team plane following the team's 3-2 victory over Roma.