CATANIA - Carlo Ancelotti has added Kaka to his extensive injury list ahead of a potentially bruising encounter at under-pressure Catania on Wednesday night.
Kaka had an x-ray on Monday that revealed heavy bruising on his injured knee, inflamed after the 2-1 weekend win over Palermo, which keeps the Brazilian from travelling to Sicily.
Further tests will determine whether Kaka will be fit for the Champions League clash against Arsenal next week.
"Kaka's absence to us is as important as (Adrian) Mutu's is to Fiorentina," Ancelotti said.
"We think he can recover for Arsenal, but we will see over the next few days."
Ancelotti does not envisage Kaka will be fit for Saturday's game against Lazio, and will also be without several other first-team regulars.
"(Kakha) Kaladze, (Andrea) Pirlo and (Marek) Jankulovski are tired and need some rest," the coach said.
Alessandro Nesta (thigh) also misses out but may recover for Saturday.
Ronaldo is a long-term injury in attack, however in his place Filippo Inzaghi stepped off the substitutes' bench against Palermo to strike an injury-time winner as AC Milan came from behind to win 2-1 and move up to fourth place in the table.
Inzaghi is set to start, with Alberto Paloschi recalled to the bench after scoring the winner in a reserve fixture on Sunday.
Goalkeeper Dida (back) is still out, while Zeljko Kalac has been training regularly despite his finger still being swollen.
"For a week I will play again with painkillers, then I hope it will improve," said the Australian goalkeeper.
Ancelotti also will have Paolo Maldini, who returned to training on Monday, though he knows it will be tough for his side to force a win in Sicily.
"(Catania) are a team that has lost some safety in recent matches, and gone back into the 'hot zone' of the league," he said.
"We will find a team with some fear but at home they have always done well."
Milan have not won at Catania in 44 years, and the Sicilian's home record has been good this season in spite of their recent dip in form.
They lost 2-0 at in-form Empoli on Sunday, a fourth-consecutive defeat and a sixth in eight winless games.
That run has dropped them from relative comfort to 15th place, only a point outside the relegation zone.
Catania players have between them picked up 72 yellow and five red cards this season, and will hope to recover some of the fighting spirit which knocked AC Milan out of the Coppa Italia.
They have no suspensions but Giacomo Tedesco (back) and Japan forward Takayuki Morimoto set to miss out with injury, whereas defenders Cristian Silvestri and Christian Terlizzi have fitness doubts.
