Cristiano Ronaldo admitted at the World Cup on Sunday he is not the player he once was but came out fighting against critics "trying to kill me for the past 23 years".

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".