The reigning European champions are still not assured of their place in the last four of the competition, having collected four points from the six on offer to sit second in Group A - one point better off than hosts Russia.
Portugal face what should be their easiest fixture thus far when hosting the Kiwis, however, meaning that Ronaldo - who has started both previous games and collected the man of the match award in each - could be afforded a breather.
Asked about his plans to rest the Real Madrid ace, Santos told reporters: "I'm not going to tell you who is going to play or not. I don't know if I am going to play with or without Cristiano – I don't want the opponents to know.
"Rotation will take place, that I can tell you. I'm just concentrating on this game. One step at a time. If you go two steps at a time you might stumble."