9th November 2016. By Ryan Baldi.
It seems strange to consider a player's potential unrealised when they finished their career with two World Cup winners' medals, 15 Wold Cup goals, a UEFA Cup, a Cup Winners' Cup, two domestic titles and over 350 career goals.

If it was ever possible for a player who represented Barcelona, Internazionale, Real Madrid and AC Milan to have never reached the heights of their early promise, then it was Ronaldo.

The buck-toothed Brazilian superstar burst onto the scene in the mid-1990s by scoring goals and shredding defences in a manner that would have made such all-time greats as Pelé and Diego Maradona raise their eyebrows in disbelief.

Having moved to Europe to join PSV Eindhoven as a teenager in the summer of 1994, Ronaldo appeared to possess a combination of athleticism, speed, finesse and skill that was unlike anything the football world had ever seen. He'd come to take over.

In recognition of his burgeoning potential, Carlos Alberto Parreira selected a 17-year-old Ronaldo as part of his squad for the 1994 World Cup in the USA. The teenager was an unused substitute as the Selecão became world champions for the fourth time. But by calling up the Cruzeiro youngster and allowing him to experience life inside the major tournament goldfish bowl, Brazil were playing a long game that they hoped would benefit them when defending the famous trophy four years later.

And it very nearly did. By the time the 1998 World Cup rolled around, Ronaldo was the undisputed best player on the planet and, as such, was expected to fire Brazil to their fifth world title.

After setting the tournament alight with some stupendous performances, four goals and three assists, Ronaldo took Brazil into the final against host nation France. But in a story which has since gone down in football folklore, Ronaldo was conspicuously off key in the showpiece event which was supposed to mark his coronation as one of the all-time greats at just 21 years old.

The striker supposedly suffered a seizure the night before the final. The incident was kept under wraps, which led to widespread shock when the initial team-sheet had Edmundo named in the Internazionale forward's place.

After great confusion, Ronaldo did make the line-up but was a shadow of the man who'd terrorised the likes of Chile, Denmark and the Netherlands in the earlier knockout rounds. Brazil lost 3-0. Despite his ghost-like performance in the final, Ronaldo was named player of the tournament.

It was an unusual occurrence but one that you'd have backed Ronaldo to overcome and go on to reach even greater heights. But the preceding four years saw the Brazilian megastar beset by a series of serious knee injuries for which he still bears the scars to this day.

An incredible return of 54 goals in 57 games during his two seasons in Eindhoven earned Ronaldo a world record $19.5 million move to Barcelona. Still only 19, the prodigious star was an instant hit at the Camp Nou, scoring 47 goals in 49 games to help the Catalan giants win the Copa del Rey and the Cup Winners' Cup. Mid-way through his maiden season in Spain, the Blaugrana man was named the FIFA World Player of the Year, becoming the youngest player to win the award at 20 years old.

Ronaldo's stay in Catalonia lasted only a year. Inter made an offer that Barça couldn't refuse, bidding $27 million another world record fee.

Great things were expected of the man who had become known as 'Il Fenomeno', the Phenomenon, and he didn't disappoint, finishing as Serie A's second highest scorer and netting a total of 34 goals from 47 games in all competitions. Another FIFA World Player of the Year award was secured and coupled with the Ballon d'Or.

At this stage, Ronaldo's game was developing at an exponential rate. In Barcelona, he'd become known for his incredible power and ability to dribble past several defenders at a time. But in Italy he was becoming a much more diverse threat, adding assists to his game and scoring from free-kicks. His incredible footwork and speed of movement also seemed to reach a level that would previously have been deemed humanly impossible.

In the 1997-98 UEFA Cup final, Ronaldo scored one of the greatest goals in the competition's history, bamboozling Lazio goalkeeper Luca Marchegiani with a series of step-overs before calmly rolling the ball into the net. It was the final goal of a comfortable 3-0 victory for Inter; Ronaldo was named man of the match.

The Brazilian's second season in Milan, following the fateful '98 World Cup, began in equally prolific fashion, but injuries restricted him to just 19 Serie A appearances (he still managed 14 goals).

The following summer, the Nerazzurri broke the world transfer record again to sign Christian Vieri. Inter fans had high hopes that the Italian international would form a stellar partnership with Ronaldo and end their scudetto drought which stretched back to 1989.

But it wasn't to be, as Ronaldo suffered the first of his serious knee injuries in a game against Lecce in November 1999. He re-appeared for the Coppa Italia final first leg against Lazio in April 2000, but lasted just seven minutes before suffering a recurrence of the same injury; he would miss the entire 2000-01 season as a result.

After a series of operations, Ronaldo returned to the Inter first-team picture towards the end of the 2001-02 season, hoping to prove his fitness ahead of that summer's World Cup. His seven goals from 10 games helped the Milan giants contend the Serie A title, until defeat on the last day of the campaign saw them slip to third.

Ronaldo, now fit again, was seen as a risk very much worth taking for Brazil manager Luiz Felipe Scolari ahead of the World Cup in Japan and South Korea.

Brazil were unfancied going into the tournament and Ronaldo, despite his return to form for Inter, was regarded as yesterday's man, a relic of the '90s who'd been forgotten about and usurped while off the radar.

That viewpoint proved to be extremely misguided as Ronaldo, with a supporting cast of Ronaldinho and Rivaldo, led the Selecão to a fifth World Cup triumph. With eight goals from seven games, quarter-final opponents England were the only side able to prevent the number 9 from equalling Jairzinho's 1970 record of having scored in every game at a World Cup.

A move back to Spain, this time to join Real Madrid, saw Ronaldo once again elevated to the status of one of the best players in the world. He was again crowned World Player of the Year in 2002.

As part of the Galácticos along with the likes of Zinedine Zidane and Luis Figo, Ronaldo enjoyed a successful time at the Bernabéu. In four-and-a-half years with Los Blancos he scored 104 goals and won two La Liga titles before joining AC Milan in 2008 and then finishing his career back in Brazil with Corinthians.

Though he was still one of the most feared strikers on the planet, Ronaldo was never quite the same player after his injury-wrecked spell with Inter.

His feet were still quicker than most but a far cry from their pre-injury level, where his torso would often appear to be floating above a silver blur.

It's a credit to the player that he sought to adapt his game. No longer able to breeze past opponents on runs from the halfway line, Ronaldo instead began to specialise in bursts of speed over short distances. He started to play more on the shoulder of defenders, looking to run in behind rather than collect the ball in deeper areas.

His status as a legend of the modern game is assured, and he'll be remembered as possibly the most fearsome and complete number 9 the game has ever seen.

But it's hard not to wonder just how good Ronaldo could have been had his upward trajectory not been unfairly halted.