Ronaldinho would welcome Kaka return
Kaka's father and agent was spotted at Milan's headquarters on Thursday but the club said he was there for "bureaucratic reasons".
"If he did return to Milan I would welcome him. He is a great champion and made history with this club," Ronaldinho told reporters after committing his future to Milan for at least the rest of the season.
Media in both Italy and Spain have said Kaka, who has struggled with form and fitness at the Bernabeu, could leave Madrid in January along with potential Inter Milan and Juventus target Karim Benzema.
Inter president Massimo Moratti denied reports earlier in the week that he had held negotiations to bring Kaka to the European champions.