Kaka has struggled to make his mark at the Santiago Bernabeu since joining from Milan for €68.5 million in 2009.
Injuries over the past seasons have also prevented the Brazilian international from regaining the form that won him the FIFA World Player of the Year in 2007.
And his future at Madrid has been surrounded by uncertainty with a return to the San Siro widely speculated.
Now Brazil team-mate Pato has warmly invited his compatriot back to AC Milan.
"I'd love to see Kaka return to Milan. We would welcome him with open arms if he decides to move on," Pato was quoted as saying by Sky Sport.
The young attacker also discussed the upcoming derby against rivals Inter and made it clear that he's confident that he'll be recovered from his ankle injury in time for the match on April 2.
"There's still a lot of time to recover before the derby. My ankle is already feeling a lot better. I expect to be fully match fit in time to face Inter."
Pato sustained the injury during the second half of Milan's defeat at Palermo on Saturday which saw their Serie A lead over Inter Milan reduced to just two points.