Tayfun Korkut is confident departing Bayer Leverkusen midfielder Kai Havertz can be a success with Chelsea.

Korkut worked with Havertz at Bayer.

He told Sky Deutschland: "This is possibly the most special thing about him, his mental strength. You will not see the difference between him if he plays against Ingolstadt or Real Madrid, if he plays to avoid relegation or win a league. He always plays the same and at a high level.

"Playing for big clubs is different. It's about mental toughness. There are many nice young players out there. But to play for the biggest clubs. To play for Bayern Munich, Manchester United or Chelsea, you need something more than just talent. This guy has it.

"It's not about being able to shoot fantastically well or because he can hit the last pass, even if he can do these things. It is thanks to these mental qualities. That is the difference."