The Blues centre-back, who had Mourinho as a manager for one year at Stamford Bridge, sun his praises.
"He is the one who opened the door of England to me. I was only 19 when I arrived there. That's young. It's also him who gave me belief by playing me in big matches with a lot of intensity," he told France Football.
"It is also he who showed me what football in England was about. The coach is a man who detests losing. He taught me to hate defeat.
"Thanks to him, I got to enjoy myself at Chelsea. He has given me a lot of things and taught me an enormous amount. I thank him."