World Player of the Year Kaka will have knee surgery on Friday after meeting a specialist in Brazil, AC Milan said on Thursday.
"AC Milan communicate that Kaka will be subjected to an arthroscopy operation tomorrow on his left knee," the club said in a statement on their Web site.
"The time of recovery will be given at the end of the operation."
Milan said the surgery will be performed by Jose Luis Runco, the Brazil national team doctor.
Brazil's Globo television reported on Wednesday that the surgery would put Kaka out of action for about 15 days, ruling him out of friendlies against Canada and Venezuela.
He could also miss next month's World Cup qualifiers away to Paraguay and at home to Argentina, according to the report.
On Sunday, AC Milan said they would not allow Kaka to take part in the Olympic Games tournament as an over-age player. The 26-year-old has been troubled this season by fitness problems.