HOUSTON : Cristiano Ronaldo is preparing for his sixth World Cup as if it was his first, said Portugal coach Roberto Martinez as he hailed the 41-year-old as "an example and a reference for football."

Armed with a richly talented generation, Portugal are among the favourites to win the World Cup for the first time.

Ronaldo's continued presence in Martinez's team has sparked debate over whether he is still a positive influence.

No one can match the five-time Ballon d'Or winner's 143 international goals. But he has failed to net in his last nine matches at major tournaments and offers little in a defensive role when the opposition are in possession.

Martinez, though, has no doubt he remains Portugal's best option up front.

"He is an example and a reference for football. For all those children on the street who begin to feel the love for sport, following the example of Cristiano Ronaldo is wonderful," Martinez told a press conference ahead of Portugal's World Cup opener against DR Congo.

"It is his sixth World Cup, but I can say that internally it seems to be his first World Cup in terms of intensity, in terms of emotional output, of how important it is for him to be prepared to lead the group.

"Within the team he is a vital player because he is the finisher, he is the player in the penalty area, he is the player who has those movements that can open spaces for other players. Within our attacking game, his numbers reflect the importance he has."

Bruno Fernandes said his first experience of a major tournament as a child came on home soil, when a 19-year-old Ronaldo helped Portugal reach the final of Euro 2004.

"All of us in this national team we have grown up watching Cristiano Ronaldo play and for us it's such an honour to play next to him now in the same team," said the Manchester United captain.

"We're all here to support him and to support Portugal to go as far as possible."

Fresh from winning Premier League player of the year accolades, Fernandes is part of one of the strongest midfields in the World Cup.

Vitinha and Joao Neves have recently won a second consecutive Champions League with Paris Saint-Germain, while Bernardo Silva is set to join Real Madrid after a trophy-laden nine years at Manchester City.

"We have a very strong team, great individual quality, and beyond the individual quality and the strengths that we have as individual players, I think we are a very cohesive team, a very united team," added Fernandes.

"Obviously our dream is to be there (winning the World Cup) and I think that dreaming is not forbidden."

Portugal will also face tournament debutants Uzbekistan and Colombia in Group K.

Martinez, though, warned against looking beyond DR Congo after the shock Spain suffered in being held 0-0 by Cape Verde in their opening match.

"We've got very little to win tomorrow from the outside. If you win against Congo, it's expected. If you win by one, it's a big problem. If you draw, it's a catastrophe. If you lose, this is the end of the world," said the Spaniard.

"They come with no expectations, they are enjoying being here. We've seen incredible performances from teams like Qatar, Cape Verde, exemplary performances, that shows you that there are no easy games in a World Cup."

Martinez also confirmed reports he is set to leave his role after the World Cup when his contract expires.

"My contract ends after the World Cup. This is not news, this is just a fact," he added.

"We're now focused on finishing the work that we've begun three-and-a-half years ago.

"When I came to Portugal the focus was to try to win everything, but most importantly to prepare for the World Cup."