Kevin De Bruyne has criticised Jose Mourinho, saying he "only spoke to him twice" during the Belgian's uneventful time at Chelsea.
The midfielder signed for Chelsea from Genk as a 20-year-old in January 2012 but failed to establish himself at Stamford Bridge and was soon moved on to Wolfsburg.
His form in the Bundesliga, which saw him named Germany's Player of the Year last season, persuaded Manchester City to break their transfer record for the second time this summer as they signed him for a fee understood to be around £55million ($85.4m).
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The fee raised eyebrows given his previous spell in England but there may have been underlying factors behind De Bruyne's failure at Chelsea.
"I only talked with him twice, Mourinho," De Bruyne said.
"One was before a game against Basel, where he said I was doing better in his opinion and that I would get my chance. I think that was maybe November (2013).
"Then one week before January, that's when I said I wanted to go because even if I was training better, I was not getting any minutes."
"I'm not somebody who talks a lot with the coach. I didn't do it in Wolfsburg and I didn't do it at my other teams. I'm not the most open player, I'm not the biggest clown. I just try to do my thing.
"Of course, you want to know sometimes what he thinks or what he thinks you need to do.
"It's the most difficult thing for a player when they say you are doing good, that's what you read in the press, but you don't know what you are doing wrong. That was maybe the biggest part that went wrong [between me and Mourinho at Chelsea]."