Kaka has sided with Lionel Messi over former Real Madrid teammate Cristiano Ronaldo in the debate as to who is the best player of their generation.
Messi and Ronaldo have dominated football over the past 12 years, winning 11 of the Ballons d'Or in that time with Messi claiming six and Ronaldo five.
Kaka joined Real Madrid in the same summer as Ronaldo in 2009 and played alongside the club's all-time leading scorer for four years at the Bernabeu, but he still ranks Barcelona talisman Messi above his perennial rival.
"I played with Cristiano and he's really amazing, but I'll go with Messi," Kaka said during an Instagram Live video.
"He's a genius, a pure talent. The way he plays is incredible. Cristiano is a machine. It's not just the way he's strong, powerful and fast; he's strong mentally.
"He always wants to win and play. To be the best. For me, that's the most incredible thing he has. In the history of sport, they [Messi and Cristiano] are definitely in the top five. We are very lucky to have been able to see both of them."
Messi is currently narrowly leading Ronaldo in the career goalscoring stakes with 627 in 718 games compared to 626 goals in 838 outings for Ronaldo.