The Brazilian was in and out of the side under Jose Mourinho and will have to improve his physical condition if he is to make a mark under the Italian
The Italian worked with Kaka at AC Milan and played a big part in transforming the Brazilian from one of the world's finest prospects to a polished world-class performer.
But after leaving Milan for Madrid in 2009, the 31-year-old has failed to set the heather alight at the Santiago Bernabeu and there have even been rumors of a return to San Siro at several points over the past four years.
And Ancelotti has revealed Kaka is doing specific work to get him up to speed with the rest of the squad, but stressed he remains motivated to become a regular feature in the side.
He told AS: "He’s very motivated, as is everyone. He needed to do specific work because he needs to improve his speed. He started individual work two days earlier and we’ll see what happens in the coming days.
"I think his physical condition is going to improve. He’s very motivated; he didn’t play much last season and he wants to do better this year.”
Ancelotti was talking ahead of Los Blancos' pre-season friendly with his former club Paris Saint-Germain on Saturday, which he guided to the Ligue 1 title last season, and he admitted he is looking forward to facing his former charges.
He said: “Madrid and PSG have the same ambitions, but one is a young club and the other is the greatest in history. PSG are a work in progress and it isn’t easy, because it isn’t enough just to buy players.
"It’s clear that they have worked hard to build a great team. They bought fantastic players last season and now they need time. On the other hand, Madrid are also backed up by their history."
The 54-year-old then spoke about the battle for the No. 1 jersey at Madrid but refused to be drawn on whether Iker Casillas or Diego Lopez would become his first choice goalkeeper.
"What’s most important is that we have two very good keepers who have experience and quality. I think that’s what we need for next season: two high-quality keepers."