The AC Milan midfielder sustained damage to the anterior cruciate ligament in his right knee during Sunday's 1-0 triumph over Catania.

The Italy international had a consultation with specialist Dr Martens in Antwerp today, after which it was announced he would go under the knife on December 19.

"I take it as a new challenge, another battle to win," said Gattuso. "I am saddened but one has to look ahead.

"I have won so many challenges in the past and I am sure I will win this one too.

"I always say that in life there are worse things and you cannot be desperate.

"I will try to recover as soon as possible."

No official timeframe has been given for his return, but Gattuso could be out of action for six months, which would be the longest time he has been sidelined for in his career.

A statement on the club website, www.acmilan.it, read: "AC Milan would like to announce that the player Gennaro Gattuso will undergo surgery on his right knee on Friday December 19 at Anversa."

His absence will be a blow for Milan and Italy.

The Rossoneri lie third in Serie A, level on points with second-placed Juventus, six points behind leaders Inter Milan.

Team-mate Andriy Shevchenko said: "His misfortune was a shock to us. On Sunday he finished the game, he was fundamental as he always is.

"I'm really upset by what's happened to him. He's a leader for us, we'll miss him greatly.

"For some of our players, especially in midfield, this is an important time, but the thing I most want to do now is to wish for Rino to get better as soon as possible.

"I'm convinced that during his rehabilitation period his presence alone at Milanello will be important."

The experienced midfielder is also expected to miss Italy's World Cup qualifiers against Montenegro and the Republic of Ireland in March and April.