Too often Ronaldo's career is looked upon as one big 'what-if'. 

El Fenomeno might well have become the greatest player of all time had injuries not held him back. 

Let's not forget, however, that he remains Brazil's third-highest goalscorer of all time (behind only Pele and Neymar) and won two World Cups. 

He was also twice named World Player of the Year. 

The world really was his oyster in the 1990s - but then came that horror knee injury while playing for Inter Milan. 

The striker fell to the ground screaming in agony, with his former physiotherapist claiming that his kneecap "exploded" in "the worst football injury" he'd ever seen. 

By 1999, Ronaldo had already complained of pain in his knee injuries and then came his most notable setback. 

It's incredible to think that having missed the entire 2000-2001 season and much of the following campaign, he went on to win another World Cup in 2002. 

Ronaldo had to adapt his game, naturally. He no longer possessed the lightning pace which frightened defenders in his early years. 

But the forward still had world-class ability in barrels, as he showed in June 2004 in a World Cup qualifier against Argentina. 

What made that night an even greater triumph for Ronaldo was that by that stage of his career, many had started to write him off - though he was still only in his late 20s. 

As he scored a hat-trick past the Albiceleste, the commentator couldn't help but revel in Ronaldo silencing his critics: "And they say he's fat - he can't run!" 

Ronaldo helped Brazil to a 3-1 win past a star-studded Argentina side featuring the likes of Hernan Crespo, Javier Zanetti and Juan Roman Riquelme. 

The most damning comment on his physique came later on from Sir Alex Ferguson, who called him the "fat, old Ronaldo" when comparing him with a young Cristiano. Ferguson later apologised for the joke, which the Selecao legend called "disrespectful" and "not classy". 

But it was a joy to see him rolling back the years in a Brazil shirt. 

Indeed, despite concerns over his weight persisting through the rest of his career, Ronaldo did go on to feature at the 2006 World Cup after helping the champions qualify with 10 goals in 15 appearances.

When he got to the tournament in Germany, he only managed a brace against Japan and a goal against Ghana, as Brazil bowed out at the quarter-final stage with a 1-0 defeat to France.

That still saw him pass Gerd Muller as the World Cup's all-time record goalscorer (a feat since beaten by Germany's Miroslav Klose). 

We rarely delve into the mid-2000s when reminiscing about the peak of Ronaldo's career, but it shouldn't be forgotten that he was still capable of producing game-changing performances like the one against Argentina. And it came a year after he had netted a hat-trick at Old Trafford to defeat a certain Sir Alex...