This day in history of Ronaldo
The Agora newspaper said: "This hairstyle is neither a mohican, nor a 'baldy', but it is very dodgy indeed."
The Folha de SP newspaper, which says it doesn't like the style, is asking its website's readers for their reactions.
Of the thousand-plus people who responded, 79% think the haircut is "awful" while 14% think that if Brazil win the World Cup Brazilians will start to copy it.
A voter identified as Rufus wrote: "Ronaldo's new look is horrible. Does he have a mirror in his room?"
Another named as Spiderman said: "The haircut is really ugly. I think that maybe it's a strategy to scare away the Turks."
The debate has also reached Argentina, where the Ole newspaper asks: "Have you had too many caipirinhas?" Caipirinha is a traditional Brazilian alcoholic drink.
Ronaldo's teammates have also had their say about the haircut.
Cafu, the Brazilian captain, told the Terra Noticias Populares newspaper: "Ronaldo arrived for breakfast and asked what we thought of the haircut. Of course, everybody laughed and made fun of him. Let's see how long he keeps this ridiculous haircut."
Ronaldo told the Agora SP newspaper: "It's a new, original hairstyle. I cut it myself. Don't you like it?"