The 25-year-old has a knee injury which will keep him out against the Biancoceleste and could also prevent him taking to the pitch when Milan face Arsenal in the return leg of their Champions League last 16 clash next Tuesday.

But the World Player of the Year on Thursday put pen to paper on a contract extension which will tie him to the Rossoneri until the summer of 2013.

And that was enough to bring a smile to the face of club vice-president Adriano Galliani.

"Kaka has declared many times his wish to become a symbol of this team," Galliani said. "He is the best player in the world.

"He is a symbol of the football displayed by Silvio Berlusconi's Milan and he has decided to tie his future for a definite period to the Rossoneri colours.

"Kaka has taken this decision. I hope that in 2013 we can make him another contract in order for Kaka to remain at Milan for life and continue to delight our fans."

The Rossoneri will be hoping Kaka's absence will not hinder their team this weekend as they look to close the two-point deficit on fourth-placed Fiorentina, who hold the last Champions League qualifying spot.

Injuries have been a problem all season for a Milan side which has drawn three of their last four Serie A encounters, including their midweek 1-1 stalemate at Catania.

"It's a pity because against Catania we missed a chance," said coach Carlo Ancelotti. "We took the lead and failed to defend it and had to settle for a draw.

"The problem is that we've had a busy schedule and we have been unable to manage well all of our games."

The Rossoneri will nevertheless fancy their chances against Lazio.

Milan have won four of their last five league encounters against the Roman club at the San Siro and their last defeat against the Biancoceleste dates back to 1989 when an own goal by Paolo Maldini gave Lazio a 1-0 win.

Struggling Lazio go into the encounter looking for their first victory on the road since October 21.

Delio Rossi's side have been unable to repeat the form which saw them finish ahead of AC Milan in Serie A last season.

Club president Claudio Lotito was given a glimmer of hope with his team showing an improved performance in Wednesday's 1-0 triumph over Reggina, the victory coming courtesy of a Rolando Bianchi penalty.

That result allowed Lazio to climb six points clear of the drop zone with 13 games left to play.

"Against Reggina, I have seen the spirit that allowed us to finish third last season," Lotito said. "But overall, it seems to be an isolated case.

"This year we don't play with the same character and determination as last season and the results are very different from those of last term."

Milan will be without the suspended Giuseppe Favalli while Alexandre Pato will lead the attack alongside Alberto Gilardino.