Shakhtar Donetsk chief exec Serhiy Palkin insists Mykhaylo Mudryk will prove himself at Chelsea.
The Ukraine has struggled since his 100m arrival from Shakhtar.
But Palkin says: "I said to them 'you've got a real diamond, but you should be very, very patient [with him].'
"Give this guy a little bit of time and he will show what kind of football he will bring to your club.
"I know 100 per cent that he will participate in many, many trophies for Chelsea in the future.
"Because this is a very unique boy. A unique boy with unbelievable technical characteristics."
