Ronaldo made his professional debut at the age of 16 for Cruzeiro, who play their home games at the venue for Wednesday's Brazil-Argentina clash.
"I'm normal and, like any person, I have sentiments," he told reporters. "I'm happy to come back to the Mineirao."
"It was emotional," Ronaldo said after stepping on to the Mineirao turf for the first time in nearly 10 years for Tuesday's practice session.
"At first, I was a bit nervous. After that, everything was fine."