AC Milan have confirmed that Antonio Cassano will require "minor" heart surgery after being struck down with a mystery illness following Saturday's 3-2 win over Roma.
Cassano was taken to Milan's Policlinico hospital for a series of tests after suddenly developing problems with his vision, speech and movement on the team plane following the match in Rome.
The initial series of examinations failed to diagnose the problem but it has now been revealed that Cassano suffered ischemic-based cerebral damage and will undergo an operation this week that will keep the 29-year-old out of action until next year.
A statement from AC Milan read: "The cause was identified as the presence of a patent foramen ovale septal heart, detectable only with sophisticated specialised tests. The timing of therapy established has allowed a rapid recovery and an improvement of clinical conditions that are good.
"In the coming days the player will undergo a small surgical intervention cardiology (closure of the foramen ovale), the recovery time for return to playing will be better defined after the surgery, but probably will be a few months."
AC Milan vice-president Adriano Galliani told Gazzetta dello Sport: "Cassano is joking as usual. He misses football a lot and he is disappointed because he has had to stop playing at a time when he was in great form. But I have told him that he should be calm because we will keep a place for him.
"I was extremely worried on Sunday. But I told Antonio today that he has suffered a misfortune but in that misfortune, he has been lucky.''
Cassano came on for the final 16 minutes of the 3-2 win at the Stadio Olimpico but then fell ill on the way back to Milan. The Italy international wanted to return home but was convinced to go to hospital by the club's chief doctor Rodolfo Tavana.
The former Real Madrid player, who last month revealed he would retire from football in 2014, has been in excellent form and returned to the Italy squad after a two-year absence last year. He proved crucial in helping Italy secure a spot at Euro 2012, scoring six goals in ten qualifying games.