Ronaldo teased and tormented the dazed Czech Republic to distraction before his second-half header sent Portugal into the last four with a deserved 1-0 win over limited opponents.
The world's most expensive player met Joao Moutinho's cross after 79 minutes to secure Portugal, who are in the semi-finals of a European Championship for the third time in the last four tournaments, a clash with holders Spain or France on Wednesday.
"I think we have showed quality and consistency," said Portugal coach Paulo Bento. "We had the capacity to react. We switched well from defence to ttack."
"It doesn't matter who will be our opponents, be it France or Spain," Bento added. "We will do the best to reach our goal."
It was surprising it took Bento's side so long to break down the Czechs, who badly missed injured playmaker Tomas Rosicky and failed to trouble Portugal keeper Rui Patricio throughout.
"We had a lot of opportunities. The Czechs did not have any - that's a great game," the Portugal captain told reporters.
"I think the chances [of reaching the final] are 50/50 and we just have to believe in it."
With 35 goals for his country, the 27-year-old will no doubt go on to surpass Eusebio (41), and then Pauleta (47) as Portugal's top scorer. The debate over whether he, or Argentine Lionel Messi, is the best of a generation will rage on.
The only blot on Portugal's victory came late in the first half when striker Helder Postiga went down clutching his right hamstring and had to be carried off the pitch on a stretcher.
