By ESPNSTAR.com staff
Ronaldo arrived on cue in the six-yard box to nod in Joao Moutinho's cross on 79 minutes to secure a 1-0 result for the Portuguese against Czech Republic on Thursday.
Portugal will play the winner of Saturday's game between world champions Spain and France in the last-four.
Pepe acknowledges it will be tough for Portugal to win Euro 2012, but having his Real Madrid team-mate Ronaldo in the squad makes it an achievable dream.
"The more you talk about Cristiano Ronaldo, the stronger he gets. He is a player from another world. To him, being the best in the world means little. He is outstanding," he told RTP.
"On the field of play, I look at him and I think he is from a different planet. He outdoes himself in every game he plays."
He added: "It will be hard to win the Euros. It is a dream we have, but we will have a very difficult game in the semifinals.
"Neither Spain, nor France, are easy. One of them is the world champion, while France are playing well again and have great players. Their team is more balanced now. All we have to do is get ready, to win the match."
Read ESPNSTAR.com writer Gabriel Tan's views on why an over reliance on Ronaldo is actually bad for Portugal.