After becoming the all-time record scorer in a swift space of nine seasons at Real Madrid with 450 goals in 438 games for Real, Ronaldo has yet to open his account in Italy.
The club-record signing has now been warned that Italian football is not about individualism - as he thrived within the system allowing him to score freely at the 13-time European champions.
"I wouldn't say that the Italian league is more difficult or better than other leagues but it does require more attention," he said after the victory over Parma.
"We, the coaches make sure our defences are well prepared and no team will gift you anything. Here, it's almost impossible for a player to score 40 goals in one season.
"It has happened once but that was a one-off during a strange season. It's more normal for a player to end with 26 or 27 goals but having said that, the team with the top goal scorer doesn't generally win the league."