The 41-year-old Portugal superstar was in turns bullish, jovial and sentimental on the eve of the last-16 showdown with Spain at the home of the Dallas Cowboys in what will be his last World Cup.

One of the finest footballers in history, the former Manchester United, Juventus and Real Madrid superstar refused to say when he will end his international career.

But to numerous questions about what lies ahead and the flak that has come his way in recent years, Ronaldo conceded that "I am not the player I used to be".

But the attacker and Portugal skipper said "I am not doing too bad", pointing out that he has scored three goals in North America -- two against Uzbekistan in a 5-0 thrashing in the group phase and a penalty in the 2-1 win over Croatia in the last 32.

Relishing taking on journalists eager to ask about his future and the harsh spotlight on him, he told reporters: "It's been like this since I was 18, it is not going to change.

"I always put body and soul trying to get our goals -- playing or not playing, I will always have an important role to play.

"As I said before, (I will stop) when I choose, not when you choose, you always ask the same question.

"I don't want to draw attention to this because it is less important."

- 'Waste of time' -

Ronaldo said this was the World Cup he had enjoyed the most, citing the "emotions" of it on and off the pitch.

Asked again about his international future, he shot back: "You have been trying to kill me for the past 23 years, but you must have seen that is not worth it, it's a waste of time, but you try and try and try and try and try.

"I am so used to this," said the veteran, who is the leading scorer in the history of international football.

Ronaldo, who was clapped out of the press conference, added: "I am not going to be more Cristiano Ronaldo or less because I win the World Cup."

"Age gives you maturity and experience to see how relative things can be," he said.

"I even say thanks for the attacks I feel after I turned 40... the criticism is how you grow, so thank you for doing this."

Ronaldo even picked out one reporter because "I know he does not like me" and challenged him to ask a question.

"To speak to you, some of you, those who do not like us especially -- I remember people's faces very well," he said grinning.

"Listen, I am going to be honest: whatever happens tomorrow, Cristiano Ronaldo will leave with a clear conscience -- not 100 percent but 1,000 percent because in life and football I gave everything."

On the encounter in Texas with Spain, a country he considers a second home after playing for Real Madrid, Ronaldo conceded Portugal were underdogs.

"It's going to be a very hard battle," he said.

"We need a lot of faith, we need to run and we need to be brave."

Subscribe to beIN SPORTS!