The Italy international was operated on after falling into a hole between the two dugouts in a training game against fourth division Itala San Marco's youth team, injuring his head and left wrist.

Gattuso broke and dislocated several bones in his left hand and immediately underwent a half-hour operation.

"Gattuso broke his metacarpus and dislocated all his fingers in his hand," Italy team doctor and surgeon Enrico Castellacci told Sky Italia after operating on the player.

"We tried to fix the dislocated bones without an incision and we succeeded. He's now awake and more calm. He's calm and happy with how things went.

"Recuperation time? That will also be evaluated by the Milan doctors, but I think that he will be out for at least a month if we are lucky."

Italy coach Marcello Lippi has called up Palermo youngster Antonio Nocerino as a replacement for Gattuso.

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The loss of the combative midfielder is a big blow for Milan as they look to get their season off on the right foot after last year's fifth-placed finish.

But Gattuso is not too downhearted following his operation and is looking forward to helping the Azzurri once more if he has recovered when their World Cup qualifying campaign resumes against Bulgaria next month.

"The operation went well," said Gattuso. "There are worse things in life.

"I am very close to these colours. I will make war against anyone who tries to stop me from playing in the national team."