Riccardo Montolivo was carried off on a stretcher after half an hour of the 1-1 World Cup qualification draw between Italy and Spain on Thursday, with Milan announcing on Friday that Montolivo was due to go under the knife on an injury to the anterior cruciate ligament in his left knee.
The 33-year-old has now had his operation and will be sidelined for five to six months as a result.
“Milan announce that Riccardo Montolivo underwent medical surgery Saturday morning for the reconstruction of his left knee anterior cruciate ligament,” a club statement reads.
“The surgeon Professor Doctor Herbert Schoenhuber is satisfied with the result of the surgery.
“The recovery time will be five to six months, unless complications arise.”