As one of the brightest coaching minds of his generation, it's not often that Jose Mourinho gets things wrong. But in the case of Kevin De Bruyne, there is no doubt that the outspoken Portuguese manager's judgement was flawed.
The duo worked together during Mourinho's ill-fated second spell in charge of Chelsea, when he barely afforded the talented attacking midfielder any playing time and was happy to sell him to German outfit Wolfsburg, where he subsequently emerged as one of the most sought-after players on the continent.
That Mourinho failed to see De Bruyne's undoubted potential is made all the more surprising considering the pedigree of the flame-haired attacker. De Bruyne began his professional career in Belgium with Genk, where he was an important part of their 2010–11 Belgian Pro League success.
Some 12 months later, the youngster joined Chelsea's ever-expanding ranks of promising young players. Initially, and perhaps unsurprisingly, he was used sparingly by the Stamford Bridge club and was soon loaned out to Werder Bremen, where he impressed during a season-long loan deal.
De Bruyne returned to west London at the end of the season and was eager to fight for a place in the first-team under the club's newly-appointed manager. But Mourinho – who is not noted for giving young players their chance – instead opted to pick older, more experienced players in the attacking midfield roles. And so, once more, De Bruyne was left looking elsewhere for regular football.
The Belgian subsequently claimed Mourinho did not give him a fair chance to impress for the Blues. "He called in all the attacking midfielders," said De Bruyne of his final weeks with the club, according to the Daily Telegraph. "He showed us the stats of his six players – assists, goals, passing percentage, key passes, dribbles. He wanted to prove I didn't perform on the level of the others.
"I simply answered him: 'Sorry, that's not logical. I've played less games than the others. How can you compare me to the others?' That was just not fair in my eyes."
The following January, and with little competitive football behind him, De Bruyne made the career-changing decision to sign for Wolfsburg for a fee in the region of £18m ($26.3m). In two seasons at Volkswagen Arena, the Belgium international established himself as one of the best and most exciting young players in world football.
De Bruyne was named the 2015 Footballer of the Year in Germany, in light of his eye-catching performances throughout the campaign, during which he scored 16 goals and provided 27 assists. By now, it was apparent that his long-term future lay elsewhere as a host of European clubs were linked with a big-money move for his services.
But it was Manchester City who produced the most eye-watering offer, worth around £55m ($80.3m), after a protracted transfer saga. And although he endured an injury-hit first season at the Etihad Stadium, the Belgian was consistently among City's better players when he did take to the field.
This summer, De Bruyne – who made his international debut in 2010 – will look to further his burgeoning reputation as a key player in Marc Wilmots' talented Belgian side. If he can inspire the Red Devils to an against-the-odds success, De Bruyne will become a national hero at the tender age of 24.