Kevin De Bruyne says it was unfair treatment from Jose Mourinho that ultimately led to his departure from Chelsea in January 2014.
The Belgium international – now starring for Manchester City having signed from Wolfsburg at the start of the season in a £55 million deal – is preparing to face his former club on Saturday.
De Bruyne previously stated that he felt like he had nothing to prove to Chelsea due to his lack of first-team action, with only two Premier League starts to his name during his spell at his old side.
Ahead of this first return to Stamford Bridge, the playmaker has lifted the lid on what he felt was unjust criticism from then-manager Mourinho, who has since been sacked, that prompted him to resist Chelsea's plea to stay put.
"He called in all the attacking midfielders," De Bruyne told the Telegraph about how Mourinho reacted after he had asked the club to leave.
"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 have played less games than the others. How can you compare me to the others?' That was just not fair in my eyes."
With Eden Hazard, Juan Mata, Oscar, Andre Schurrle and Willian ahead of him in Mourinho's pecking order, De Bruyne went on to impress at Wolfsburg for 18 months before his big-money move to City.
The 24-year-old had also been unimpressed by comments from the Portuguese boss that he had not been trying hard enough in training following his decision to leave him out of a Champions League trip to Steaua Bucharest.
De Bruyne added: "There was talk that I didn't train too much, stories I couldn't defend myself against as the sessions were always behind closed doors.
"People who know me, know it's not the truth. A few months later, I was a key player at Wolfsburg and I played a good World Cup. Who's right then? I just like to play football. Put me on a bench and I will feel bad.
"After his press conference in Bucharest I even started training harder, even on my days off. But my situation never changed. That's why I asked him in a friendly way: 'Please let me go'.
"Mourinho told me he wasn't keen to let me go, even not on a loan - 'you are a good player'. But what could I do more?
"Chelsea wanted to loan me out, even wanted me to stay, but I had enough of it. I wanted to leave."
De Bruyne has six goals and nine assists from 21 league appearances for City this season.
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