Milan's Alessandro Florenzi has undergone surgery on his left hamstring, with the Italy full-back expected to miss the next five months of the season.

The defender, a key member of the club's Serie A title-winning squad last term while on loan from Roma and a Euro 2020 champion with the Azzurri, suffered the injury during their 0-0 draw with Sassuolo last month.

Now, he has undergone an operation in Finland that will keep him out at the very least until the start of the new year, in a major blow to Stefano Pioli's side.

"Milan can confirm Alessandro Florenzi suffered a severe injury to the biceps femoris of his left hamstring, which required surgery," read a club statement.

"The surgery was successful and Alessandro will return to Italy tomorrow to begin the rehabilitation process. He is estimated to make a full recovery in five months."

Florenzi signed a permanent deal with Milan ahead of the new campaign, and had made two appearances so far this term before his injury.