Coach Paulo Bento has engineered a remarkable turnaround, improving the side's morale after replacing the sacked Carlos Queiroz in September.
He took charge after an embarrassing 4-4 home draw with Malta and a 1-0 defeat in Norway but subsequent wins over Denmark and Iceland have pushed Portugal, who are equal on goal difference with the Group H leaders, within three points of Norway.
"It is a key opportunity to go first in the group," Bento told a news conference. "We are under pressure but it is a much better kind of pressure than what we had back in October."
Ronaldo has been on fire at Real Madrid this season, netting 40 goals to set a La Liga record, and the Portugal captain and the world's most expensive player said he had one last job to do before going on holiday.
"The season is not over yet. I have an important game to play for Portugal and I want to win it," he said.
The Norwegians will miss holding midfielder Alexander Tettey (thigh injury).
"He (Ronaldo) is world class, we must allow him very little space and always have to be on top of him," Norway coach Egil Olsen said.
Fluid displays in a 4-0 thumping of Spain and a narrow defeat by Argentina in recent friendlies showed Portugal are hardly a one-man show, with Nani, Raul Meireles and Joao Moutinho carrying good club form to the international stage.
Norway, who have not reached the finals of a major competition since Euro 2000, have 10 points in the group, three more than Portugal and Denmark.
Probable teams:
Portugal: Eduardo; Joao Pereira, Ricardo Carvalho, Pepe, Fabio Coentrao; Carlos Martins, Raul Meireles, Joao Moutinho; Cristiano Ronaldo, Hugo Almeida, Nani.
Norway: Rune Jarstein; John Arne Riise, Brede Hangeland, Kjetil Waehler, Espen Ruud; Erik Huseklepp, Morten Gamst Pedersen, Christian Grindheim, Bjorn Helge Riise; Mohammed Abdellaoue, John Carew.
