The coach has revealed that the Brazilian will make his return to Serie A following a four-year absence and also defended criticism of Stephan El Shaarawy's form.
The Brazilian left San Siro in 2009 but returned to the club in the final 48 hours of the summer transfer window from Real Madrid. Allegri praised Kaka's commitment to training since his return to Serie A and acknowledged that the 31-year-old is nervous about making his return in a Milan jersey.
"I think Kaka will be in the starting XI,” Allegri said during a press conference Friday. "He is in good shape, he has trained really well and he has the enthusiasm of a young boy. I think he is a little nervous about his debut tomorrow and it is only normal that he is missing a bit of match sharpness.
"Kaka can give a lot to Milan. He has done some great things at this club. He hasn’t played a lot over the last three years in Madrid, but he has immediately put himself at my disposal. He spends a lot of the day at the training ground and he is a great example for the youngsters."
The coach also defended Stephan El Shaarawy from criticism over his lack of goals in 2013 and says he hopes that the Italy international can be motivated by being dropped from the starting XI.
"There is no problem with El Shaarawy," Allegri insisted. "It doesn’t exist. Stephan’s goals dried up in the second half of the season, but his performances remained good. It was his first season under the spotlight, but he did well.
"Since he returned from the Confederations Cup, he’s only really missed the Cagliari game. You can’t fear competition for places when you are in a great team. That needs to be a stimulus. El Shaarawy needs to stay calm because he has my faith."