Ronaldo Nazario is one of the greatest footballers to walk the planet.

What the two-time World Cup winner achieved before his 21st birthday is beggar belief, bursting on to the European scene with 101 goals in just 106 matches for PSV Eindhoven and Barcelona.

The only asterisks you can ever put over Ronaldo's career is the widely-accepted theory that he would have been even better if it wasn't for the knee injuries he suffered at Inter Milan.

Ronaldo was still good enough to become the World Cup's all-time top scorer and score twice in the 2002 final, but a better run of fitness could have seen him become the undisputed GOAT.

Injuries aside, though, Ronaldo is still considered to be the best of the best by some of the most revered names in the beautiful game, most notably former Barca coach Jose Mourinho.

Is Ronaldo the GOAT?

The 'Special One' told LiveScore last year: "If we are talking strictly about talent and skill, nobody surpasses Ronaldo. When he was at Barcelona with Bobby Robson, I realised that he was the best player I'd ever seen take to the field.

"Injuries killed a career that could have been even more incredible, but the talent that that 19-year-old boy had was something incredible."

Fair to play to you, Jose, but how does Ronaldo compare to his namesake, Cristiano, and his eternal rival Lionel Messi, who have hoovered up 11 Ballon d'Or trophies since 2008?

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Roberto Carlos names Ronaldo at the GOAT

Most fans would accept that Ronaldo had the potential to become the greatest of all time, but that ultimately C. Ronaldo and Messi have surpassed his achievements with a bit of luck on their side.

Well... that's most people and Roberto Carlos certainly isn't 'most people'.

Arguably the greatest left-back of all time, Carlos knows a thing or two about the qualities of top attacking players and he believes that the 'original' Ronaldo is truly the greatest of all time.

"Ronaldo stood out in training. He was the best. There will never be another Ronaldo 'Fenomono'," Carlos explained to Goal at the the Heineken Legends Challenge.

"Not Neymar, Cristiano or Messi – Ronaldo is unique. I think in our generation it was harder to score goals. It was more physical back then and attackers were less protected. But Ronaldo could do everything."

Brazilian defender Roberto Carlos (L) sh

Three amazing players

Is there some bias towards his former Brazil and Real Madrid teammate? Perhaps, but Carlos still makes an interesting point and selecting CR7 could similarly have been perceived as favoritest.

And although we're not entirely sure what to make of Carlos saying it was tougher to score in his era, we're hardly going to argue with a man who had that very task during the epoch in question.

For our money, injuries are what held back Ronaldo for surpassing his namesake and Messi, but all that time on the treatment table certainly doesn't stop him for entering the conversation.

Brazilian forward Ronaldo jubilates afte

Perhaps the Ronaldo vs Ronaldo vs Messi debate is how we should have phrased it all along.